I have the 4.5.0.52 and it is working well. I was able to DL the 4.5.0.55 last night and wondered if anyone had compared the 52 vs the 55 and whether it is worth the trouble to upgrade from the 52.

BTW, I am using BB Maps from an old 4.2 OS since AT&T apparently sends down an empty service book for the 4.5 BB Maps if they haven't been successful in preventing you from loading BB maps in the first place. The 4.2 BB Maps seem to get a working service book from BB. I've seen other posts about this, but wonder whether AT&T is going to relax its policy about BB Maps once the 4.5 is on their DL site. (I suspect not, since they want to sell their TeleNav program.)