It's a very good player and sounds decent with cd too. It's certainly not lightening quick but I don't think I ever had to wait 2 minutes for a disc to play and I am still using firmware v. 1.17 as I never had any problems/glitches. Many run fw 1.25 without problems but some have experienced audio
drop-outs amongst other issues, the reason I stick with 1.17 for the
moment. In any case, I really don't care to wait a minute before watching a 2 hour film. There is a lot of discussion around whether further fw updates will speed the player up. There's also some concensus that the issue is now more related to the transport used than the software itself. I believe the new players use the same transport so if that's the case, no advantage there.
I think it's more important that pioneer come up with a 'definitive' firmware update that at last includes the (almost a year) promised DTS MA coding and without introducing further operational problems in the process. The new players won't be imune to that either, so no advantage 'out of the box' there. It's no issue for me as I don't do surround etc and it won't be for you if your receiver can decode it.
If BDLive is important to you then the new players are the ones to go for. I had a quick look at the 320 which someone suggested and the price is around £160 more than the BD51 on pre-order. I think it's the same machine other than BDLive. A lot to pay for a 'gadget' that's not properly supported yet of what I can gather. I give my BD51 a live span of perhaps a couple of years as BlueRay is still in it's infancy relatively speaking. If the 320 comes down in price to similar levels as the 51 then it's an easy decision whether you want BDLive or not but in the current economic climate I can't see that happening soon.
To sum it up; Fantastic pictures, good sound, great adjustability and menu's, looks good, nice build. - Slow'ish (?), Pioneer's usual slow firmware updates, not v.2.0.
I compared it to Denon's transport only £700(900) player and preferred the Pioneer. I would perhaps compare the BD51 with one of the new panasonic players if one of them is around the same price and if you can stand the look. They seem to have fewer software problems though I'm not 100% sure about that.