Can't really say about EVF v OVF until I get to see the new OLED EVF in the A77 but  re. A55 v A580/A700 overall I prefer OVF albeit I can see some advantages to the EVF.

As for other features I would expect to see at that level (& tbh I would have expected/wanted in the A77 too)

Bigger buffer - 3 seconds @ Hi (i.e. 24 frames RAW) not 1.5.

2 card slots, 1 to be CF & ability to write RAW to 1 & JPEG to the other / stills to 1, video to the other / overflow from 1 to the other etc.

Owner/Copyright in EXIF

Tethering

Audio input level control (auto gain, 5v mic phantom power via 3.5mm stereo jack)

Keeping the form format for the battery was imo a good idea  (I have 7 batteries for my 2 existing bodies - replacing those would be £££s) but I wonder if they can improve the technology to squeeze a bit more power & hence exposure out of it? An NP-FM500H-2 if you like.

As other respondents have noted, it's essential to use both OVF and EVF cameras in order to give a meaningful answer. I had hoped to try the Nex7 and A77 at Focus this year, but clearly Sony's absence makes this difficult. I've just spent a week walking in and photographing the hills in the Lake District. Carrying my A900 and 17-35, 24-70, 70-400 and 100 macro certainly gave me a good workout (I'm in my mid sixties) so I can appreciate the potential benefits of the NEX 7. One of the members of our group sported a NEX5N and a couple of lenses; the results were rather impressive and the weight difference was significant. I had seriously intended to look at the NEX 7 for candid photography and travel photography where weight would be a serious consideration; I have no intention of trading my existing system, though, and think it is brilliant for studio and nature work.

So it looks like Sony's absence from Focus has saved me a few thousand pounds .....

I had hoped to try the Nex7 and A77 at Focus this year, but clearly Sony's absence makes this difficult.