My conference looks like this...
The biggest thing is just the lack of people - often we don't see who else is in the same "session" - and you can't easily lean to the person next to you to ask if they understood what was just said... On top of that it's all on Mexican time, so the days run from about 3pm to 1:30am. My other conference in a couple of weeks (WCCI) is at least in Glasgow, but for some reason it's not quite on local time and runs from 11am to 10pm each day. I do have a paper to present at that one but I expect I'll not be the most coherent by then!
Of course, on the plus side, I've not lost two days to travel time, nor am I away from home, so the girls can put notes like this under my door:
The food is definitely better than conference provisions, I can get a decent sleep in a non-hotel-bed, and I can see all the family in my breaks.
In short - virtual conferences aren't as good from the work perspective - but personally they are pretty good.