Logitech UE is definitely pulling out all the stops to make a good first impression. The box is sturdy and filled to the rim with stuff.
Normally, the bundle is not something worth going into great detail about, but this is an exception. For the first time, you get five differently-sized pairs of silicone tips with a set of Logitech UE in-ears, ranging from XXS to L, and three different sizes of Comply foam-tips. You also get a micro-jack adapter, a 1/4" adapter, a jewel case, carrying bag, and a spare cable.
We are definitely seeing several pretty interesting designs with Logitech's involvement in UE and the UE 900 is no exception. They have stuck with the blue color scheme of their older Triple.fi 10s, but the core design of the shells is radically different. The "stick" design of the older Triple.fi 10s has been replaced by a much more ergonomic shape. This is great in terms of comfort because you do not have a huge lever sticking out of your ear canals while on the move; however, getting them to fit properly over super small ears might prove troublesome.
The shape is perhaps best described as bell-like because of the way the body flows into the sound tube. This type of design should work well for most people, but some ear shapes are, like with all in-ear designs, bound not to work with these in-ears. The sound tube has the same dimensions as the older models from Ultimate Ears, so you can reuse older custom tips with the UE 900s.
The cables that shipped with the UE 900s are alright; they are more prone to unraveling than the quad-braid cables seen on the custom Ultimate Ears in-ears or Westone's Epic Cables. They are quite good at dampening microphonic noise, and the microphone and its remote cable work well on modern iDevices. The mini-jacks are very small, but seem remarkably durable, and they should even be compatible with devices that have heavily recessed jacks.
The only really bad call in terms of cable design is the UE 900's memory wire. There is simply no reason to include that feature on a set of consumer-specific in-ears. The memory wire makes the cable less comfortable over the ears. The only real scenario where it is welcome is if you, like many stage performers, run the cable down your back through a hard cable-twist behind your head in order to keep the in-ears from falling out while running around on stage. It is, otherwise, utterly useless.
User replaceable cables on in-ears are always nice to have. Logitech UE's version allows the cable to swivel, which improves its comfort-feel somewhat.