I've just got the PAL BDP-S470 and generally it works great on M2TS, AVCHD, BDs and MKVs - all on DVD+R, DVD+DL, BD-R and BDROM (haven't tested USB HD). It's currently got a big problem and that is the auto framerate is broken.
Set at 1080/auto, BD (ROM and BD-R) discs play at 60i unless you stop the disc then restart it, then 50hz titles change to 50i and BDs change to 24p. I cannot get any MKVs or AVCHDs to play at 24p. I've never had a problem playing these videos at 24p on my BDP-S350, (of course the MKVs were originally 1280x720 compliant AVCHDs for the S350 as it doesn't support MKV). DVDs (PAL & NTSC) auto switch framerate correctly. This is all with the 473 firmware, I haven't tested this on the previous 315 version - don't know how to downgrade.
I also have the odd AVCHD (X264) disc that has jittery playback whereas they play perfectly on the S350. Needs more testing and it possibly is bad media. I've also had the odd AVCHD disc just stop playing, restarting and it plays fine - again possibly media. Still I never had any problems like this with the S350.
Good news: resolutions other than 1280x720 or 1920x1080 always play fine, i.e. 1280x520 etc. Weightp=2 titles appear to play fine as MKV but when remuxed to M2TS/AVCHD they display the dreaded blocky corruption. Oh yes and NTSC DVDs are output at 24p, very nice!
Photos on USB Flash are just great, really fast! Also the BBC iPlayer is great (for those in Blighty!). The device is also fast at most things.
Oh and the drive is a bit noisier than the S350, it's not too bad though.
It's not going back yet, I'll contact Sony to see if they can fix this. I'm quite surprised they released this product, it still feels like it is beta, i.e. DLNA support to some in future firmwares, broken auto frame rate support. The S350 is/was such a rock solid player.
P.S. The DVD region hack here
works fine with the S470!