I'll give you a run down of my experience with GW2:
Story:
The story is okay from what I saw of it. Everything outside of my class quest was pretty forgettable, and it kind of throws you in and just starts piling lore on top of you. I'm not sure how much it ties into GW1, because I barely played that, but it took me a while to piece together all the terminology and figure out exactly what was going on. I think the story itself isn't up to par compared to say, SWTOR, but is definitely better than other games on the market.
Combat and Gameplay:
I've heard a lot of people praising the combat system in GW2, but I wasn't super impressed. I played TERA which has arguably the most intuitive combat system, and GW2 is no TERA. It's in a weird middle ground between classic tab-targetting games like WoW and active targetting games like TERA. While doing events and dungeons, I noticed the cornerstone of GW2 is 'Don't stand in shit'. This is an element in all MMO's, but in GW2 it's centerstage, well lit, and borderline invasive. Avoidable damage is quite literally the main focus of PvE combat, and it can start to get tiresome.
GW2 also mixed in platforming elements. The big problem I had with these was that I picked a race that had very large character models (Charr) and they seemed to forget to test the platforming elements for all model sizes (since they vary greatly, it's kind of a big deal) and ran into a lot of areas where progressing was either near impossible, or at the least hugely inconvenient. The jump animations were also very unsightly. I bought the game after all my friends who had played GW1, and they insisted it would have almost been better if they hadn't even added that because it looked so awkward.
My other major gripe is tied into the way the zones scale with levels. There were a lot of situations where it would scale my character down that made quests needlessly hard. It was a huge pain to go into an area as level 15 and get knocked down to 12 to fight level 13 mobs. I should reasonably be able to manhandle them, but instead every fight became more of a struggle than it should have been. This makes it feel as though your character never really progresses, because you are always being scaled to the enemies strength. Obviously you have more tools at your disposal as time goes on, but only a fraction of your characters potential is available a lot of the time.
Quests and Events:
A huge selling point for GW2 was dynamic events, and quests that were interactive and broke the standard of "Go Kill 10 Boars". We were told Events would change the landscape and alter the way players interacted with the environment. People will tell you the game is a lot more dynamic and questing is less bothersome. I'm going to tell you that "dynamic" tag is a bit misleading, the events are all largely defending points\NPC's and don't exactly change much about the game world, and the quests are the equivalent of putting lipstick on a pig.
For the Events, they are often triggered by something. I saw several events that popped up once someone in the area completed a specific quest, and a lot of them were on timers (as in, people would post that one was about to start because they were so predictable). While they are still an experience, they pale in comparison to what games like Rift have already been doing for years. In Rift, events are one hundred percent dynamic, and sometimes you can go for days without seeing a certain one. On top of that you can get multiple events at a time in Rift that overlap and have multiple forces actively fighting one another as well as the players. In GW2 this never really happens. It's mostly you defending an outpost, or sabotaging some enemy forces, or leading a party to kill a specific NPC, and sometimes they are just fancy escort quests. In Rift you have elementals that tear open the fabric of reality and pour out across the landscape at random times, or march straight out of the sea. They also lead attacks on small towns and outposts, and if they overwhelm the NPC's, they set up a point and spawn waves of their own forces that charge and patrol across the landscape. The world feels like its own place, and in GW2 I never got that same feeling.
As for quests, do not be fooled into thinking they are a huge advancement compared to games like WoW or Rift, and are definitely nothing close to what TSW has to offer. Now, instead of giving you a quest that says "Go Kill 10 Bears At Farmer Incompetant's Farm" or "Collect 10 Apples at Farmer Incompetant's Farm", you get a quest that says "Assist Farmer Incompetant At His Farm", and an ambiguous meter appears. So you may be asking, "How do I help him?" Well, by killing bears and collecting apples! It's quite literally the same exact style of quests, but you just aren't being given exact numbers. It won't tell you to kill 10 bears, but you need to kill 10 bears to "assist" him and fill the progression bar.
Character, Class, and RPG Elements:
GW2 made bold claims about breaking the trends by removing the "Holy Trinity" in favor of having all classes able to tank, damage, and heal. But here's the thing, the Trinity is very much still noticable. It's no longer you play a Priest or Pally and pick a dedicated specialization which affords you the tools to heal, it's more like you are strong armed into putting points you gain while leveling into one of several traits that give you a legup to do these things, combined with picking gear up that gives you more of those stats. But you still very much need to dedicate yourself to one role if you will. I played a Charr Guardian, which is basically a Pally. I went for a tanky build and it required me to stack stats that gave me additional damage mitigation as well as use a shield and one-handed weapon. Now, at no point did I actively pick a specialization, but it was in my best interest to pick a focus, because mixing stats around would leave you doing too little damage, or too squishy, or give you problems surviving.
Another selling point for GW2 was the way weapons work. It's a halfway point between games like FFXI where your weapon determines your class, and traditional MMO's where you need specific weapons to do specific abilities. That means your weapon determines the abilities you have access to. and you're required to "train" with the weapon (kill about 7 mobs) to unlock all of them. The biggest frustration for me is, like I said, you unlock them all after about 7 mobs. You never continue advancing after that, and it just seems like a completely pointless system once you've unlocked your 3 (I believe it was 3) abilities. You also had like 3 different sets of weapons equipped at a time--Set 1, Set 2, and Underwater. Which you were allowed to switch between to every few seconds.
As for character progression beyond the weapon system and roles, you have traits and abilities that you get points towards unlocking. They are basicaly talents. In any other game they would just be called talents. You put points into a tree that gives you passive bonuses and extra abilities every 5 or so points you put in. It's not a bad system, but as I mentioned earlier, this really forces you to focus on a specific role. Each one was very focused on either damage, healing, or tanking.
Visuals:
The game does look good, I cannot deny that, but it also doesn't take full advantage of available hardware (or at least didn't when I played the month it launched). I thought TERA was the most impressive looking game given its style and aesthetics, but GW2 definitely does well. If they could patch GW2 to use more threads, it would definitely ease the burden it places on a lot of peoples systems. I also really liked the character models--The Charr specifically.
Final Thoughts \ Verdict:
GW2 is not a bad game, but it was too ambitious and claimed itself to be a lot more revolutionary than it really was. It does a lot of things well enough that if you can get it on sale I say it's worth picking up. Its main claim was that it was "Buy To Play', and that is honestly one of the main reasons I got it in the first place. I cannot comment on endgame since I only really leveled and then moved on because the game didn't appeal to me a whole lot (plus the new WoW expansion pulled me in). In the broader scheme of MMO's, I'd say WoW is still the best, followed by Rift, and then a mash-up of other games depending on what you want (TERA for fun combat, TSW for a great story and amazing quests, SWTOR for an amazing story and good time leveling).