Racket 5.1.2 came out recently, and I’ve been pretty happy using it so far. It feels significantly snappier than 5.1.1. It also looks like some of the graphical quirks I saw in DrRacket running under xmonad are fixed.
Documentation still needs some work, according to folks on Reddit. Although Racket has a lot of good reference documentation and quite a few tutorials, the meaty libraries like the FFI are missing the kind of treatment that the Guide provides for the basic language.
Lots of work to do!