The Register have an interesting review on 11.04 here, the main big change seems to be the move from GNOME 3 to their Unity Desktop by default. It seems to have split opinion for many people.
@isabel1066 There's always WINE or failing that, a virtual install of Windows. My desktop pc is over 5 years old and can run XP on Virtualbox without any problems. It's great for the one or two windows applications I need now and then.
I haven't played around with 11.04 hugely but I do think it's a vast improvement over the old Gnome 2 desktop, don't like the way it restricts how you get to your applications though. I always use the alt-F2 to launch applications instead of searching through the menu search box.
One tip I can give is to get those pesky minimize,maximize buttons to the right side of the windows from the mac-style left hand side.
alt-F2 and type gconf-editor
go to apps > metacity > general in the side tree and locate button_layout in the main window.
modify that to whatever order you want, you need a colon to separate the left from the right of the window and a comma to separate the buttons so for example you might want menu:minimize,maximize,close for a standard windows style button layout or you could just get rid of some buttons and have :maximize,close for just those two buttons on the right hand side. This is something that always annoyed me with the themes in ubuntu, the lack of consistency with the button placements