One of my big pet peeves is forcing the user to accept your application they way someone else thinks it should be. Nearly every UI change in the last few years had not been helpful for the power users, or those that don't fit the programmer’s idea of a "typical user".
Vista, Windows 7, and the soon to be Windows 8 are bad enough, but I see Adobe not to be left out decided to get on the band wagon. I have been avoiding using Acrobat 9 Pro on most of my machines, which is fine. But I keep bumping into one machine I have Acrobat Reader X installed.
The thing I can stand about the UI is the eat up my smallish laptop screen pixels and give no value by forcing me to display options I would never use, and can't remove. In the right third of the toolbar (which can only be one row high) I can't find a way to hide these "tools" and make room for something useful.
UI designers should never restrict the users to one row of toolbars, and then also restrict them to have mandatory items show. I do have more tools selected, and it isn't like these tools are filling unused space. I actually have more tools that one row would allow, but for some reason Adobe decided for everyone that we should have these pixels reserved for what the typical Acrobat Reader user would need. In my opinion, Acrobat Reader users want to read and navigate the PDF. If they wanted to do more, there is an Acrobat Pro.
Anyway, I don't normally like to make negative comments, but I think someone needs to stand up for the user and the answer that is never wrong is "give the user what they want", which means the flexibility to customize things as they wish.