Awesome! I'm currently using Racket for a large end-user application. Apart from a few system integration issues the only downside so far is its long application startup time. I'll have to live with that.
Edit: One feature they should really consider adding is an online documentation for functions that is displayed in a status line while you type. I've found this incredibly helpful in other IDEs.
In DrRacket, you can see automatic documentation for the function your cursor is on in the upper-right corner of the window (you can mouse over it to show it, or hit F2). Is that what you're looking for?
Edit: One feature they should really consider adding is an online documentation for functions that is displayed in a status line while you type. I've found this incredibly helpful in other IDEs.