OK, my BV7-40 MKIV has been installed this morning. Here are my brief initial thoughts (in no particular order):
1) Freeview module improved. Much better layout/structure and use. No real improvement to PQ.
2) Only two (!!) HDMI sockets free out of the four advertised. Blu-ray drive uses one (a cable passed through the system and connects to one HDMI socket) and the DVB HD uses another. This is got to be the single most annoying part of the new system. Why oh why have B&O advertised 4 x HDMI sockets, but 'forgotten' to add the caveat that two of those sockets are in-use?
3) Blu-ray playback *is* better and more fluid than on the old MKIII. Watched the opening sequence on my old favourite Casino Royale, using the internal player, and the movement is more fluid, screen keeps up with fast camera panning and it's a little brighter. I'd say it's about 10-15% of an improvement watching a Blu-ray compared to the same Blu-ray on the older MKIII.
4) Internal Blu-ray drive is noisy. A bit embarrassing to be honest. Strange that we've got this top-end well crafted TV, but a really noisy internal drive. Doesn't really seem to synergise properly. It's no noisier than the PS3 drive, but I didn't pay £10K for a PS3.
5) The internal Blu-ray drive seems a bit of a hack, probably as it simply passes a cable through the a HDMI socket and is no better than an external Blu-ray player.
6) The Blu-ray player ships with a decent 'loading' screen. Using it though is a bit bizarre. You have to press yellow + > to fast forward etc. It was easier to use the Blu-ray remote with the PS3 ;)
7) Sky HD. HD channels were no step up from the previous MKIII. Perhaps a tad brighter, but definitely less than a 5% improvement. Perhaps I'll get a better impression once I've watched more TV - ie. football on HD could be interesting as the 100Hz screen should help the fast camera panning.
Worth upgrading from the MKIII to MKIV? Probably not, no. The lack of HDMI ports and the hard-to-use Blu-ray player make it more of a hassle than the previous MKIII. The PQ improvement is very small. Blu-ray improved slightly, everything else pretty much 'as is'.