The Cosmopolitan certainly is impressive: touchscreens at check-in and along the walls in the conference areas; beautiful pools; Sirius in your hotel room; and great views.
It is clearly aiming for the high-end/trendy crowd with flashy walls of video and animations and top-notch music in the elevator (LCD Soundsystem, Peter, Bjorn, and John, etc).
The rooms are clean and stylish - with a giant TV that controls the lighting and heating and ambiance in the room. The showers have a large window in them which overlook the sleeping/living area.
The room service was great - although I only ordered breakfast. They were honestly some of the best eggs I ever had.
Now, for the bad - the wake-up calls never worked - whether I set it through the TV or touch-screen phone. I nearly missed an important meeting my first day. Others in my group complained that their room wasn't serviced by 5pm, as well.
In my room - I did not have a dry cleaning slip to write-up and it took me two days longer than normal to get my dry cleaning handled because of that oversight.
You could do much worse with a hotel choice in Vegas and they still have time to get some of their problems fixed since they have only been open half-a-year at this point. I would stay here again - and will likely have to for work, anyway.