The standard class seats are alright, being lucky enough to sit in one at Newton Aycliffe a few weeks back. The charging ports are pretty much the same as a MK3, but there is a tad more legroom, about the same as the priority access seats in the GWR MK3's. There is more room overhead, and I'm 6 ft exactly and can walk fine through the carriages. As for 1st Class, it looks very similar to standard (sadly) and could really do with better seats, especially since the price difference between standard and 1st is huge, and I wouldn't say it's worth it for what I looks like.
The reasons the interiors of the first batch of 800s look the way they do is well documented - civil servants know best...
Virgin have at least been allowed to go for a splash of colour, if the artist's impressions are anything to go by, but the black and red first class seats look rather tacky to my mind.
Fingers crossed GWR has commissioned the same people who did the current HST first class to make a rather better job of the 802 interiors, though almost anything would be an improvement than DfT's shades of grey...