My review of REALbasic 2009 Release 5 (and 5.1) is up on the ARBP website in the blogs section. Direct link.
I’ve been using 5.1 exclusively the past week or so and it seems to be stable so now I can move up from R3. Thankfully, the huge SQLite bugs introduced in R5 have been fixed in R5.1. Reporting still has issues though.