Following up on the post earlier about GoPHP5, my take on 5.0 and 5.1 is that people are off talking about killer features, when I'm yet to see one. I'd love someone to actually show me these. I've mentioned a lot of details at http://www.silverstripe.com/core-team-discussion/flat/2206
Personally, I really, really like 5.2's better __toString() handling. Call it an incremental update, call it syntactic sugar, whatever. I call it (irrationally, sure) 'worth the update for that alone'.