Off the cuff comments on Sideways

If discussing things I thought were going to happen but didn't happen counts as a spoiler, this post contains spoilers for the film Sideways.
-When Maya says to Miles that she wasn't at the bar because "She had class," I really wanted him to respond, "Don't be so hard on yourself, you still have class.” I guess that’s too corny for his character though. Is that line too corny to be effective?
-The scene where the four of them go back to Stephanie’s is very Swingers-esque.
-Jack is clearly lying when he claims that he thought this trip would be the best time to give Miles a particular piece of news (news not described for the benefit of anyone who hasn’t seen the film). Maybe it can be explained by Jack’s general self-destructive streak, but it really seems out of character for him, sort of like the only reason he didn’t tell Miles earlier was because it makes the film better if Miles finds out now.
-What’s the deal with the split screen montage sequence fairly early on in the film? Parts of the montage correspond neatly to things Maya says about why she got into wine later in the movie, and the rest of it works as a nice change in the pacing of the film, so I guess I’m in favor of its inclusion, but it’s a little showy.
-For the last half hour of the movie, I was convinced, and worried, that the ending would be Miles writing the story of the movie as his book. You may remember this ending from Moulin Rouge, Wonder Boys, and every other story about a struggling writer ever. I was pleasantly surprised by Payne and Taylor’s restraint in not using it.
-The actual ending isn’t as ambiguous as it thinks it is, but it’s a nice last image.
-Overall it’s funny, original and very watchable. But I’m mystified over the raves for the acting. Giamatti was good in a low-key way, but I don’t see how the role was so difficult. And while this is certainly the best performance by Thomas Haden Church I’ve ever seen, I actually remember Wings, so that’s not saying much.