I've never read the novel, so I was worried I'd be completely lost, but it wasn't too bad. The story was obviously very pared down, and even though I knew nothing about the plot it was obvious that the opera basically serves as a 'greatest hits' and only shows the big, dramatic moments. The story jumped around a lot, but most of the sub-plots were just the bare bones, with all the focus on Anna's drama.
Karenin was surprisingly sympathetic, but that was all in the actor's performance. The way the opera is written, I think it could really go either way.
The music is very bombastic and dramatic, but the vocals are not. There would be dramatic music in the background, but the singer's lyrics would be fairly pedestrian and unimpressive. A lot of English operas are like that; I wonder if there's something about the way our language is constructed that just doesn't work for opera. It may very well be, now that I think about it. Anyway. I felt pretty underwhelmed by the singers. Too bad.