It boots into the "metro" interface, that mobile device looking poo. Its got a desktop mode that looks just like Windows 7/XP but in order to get to it you have to select it after you log in. Its just added confusion.
As for what the users don't like about it. It boils down to anything that represents a shift from their normal work modes is viewed as an obstacle to efficient work. Right now getting to their applications and files is easy and familiar. Metro, while in the end may be intuitive, its different. And that means retraining and in some cases rewriting of procedure manuals.
Might be great and lots of fun at home but in the workplace, that kind of crap is an IT department nightmare.
Yeah, I can see that... we do our own IT here and we don't like change either...
MS is dumb if they don't give people that option back... I'll never understand that mentality with software companies... more options is better, not worse.