Does the move from Vancian magic (or other subsystem changes, like fighter powers) "grow" on you?
No.
Do you still have the same issues you had when you started out?
Mostly. I won't list them as I don't want to invite edition war talk.
Do you have different issues, especially any that surprised you?
Yes, combat is longer and slower than before, and that irks me, but I did not expect it.
How long did it take for your opinion to change/cement?
To be honest it was pretty quick, but I'm still trying to like the system. It is a good game, taken on its own merit. But it's not the game I want to play. Unfortunately I'm stuck with it for the time being. I probably count as one of those being 'forced' to play 4E. My advice is to run a few more test games (Do NOT use KOTS!) and then see how your players feel. Sticking with 4E when player's aren't happy with it is not a good move for the group.
Did anyone else in your group have a change of heart (in either direction)?
Not that I've noticed no. We're all (except 1) trying to be open minded about it, and still playing and trying to make it feel better, but we're not making headway.
Again, my advice is to run some more test games, but not to force the issue. I suggest running games that do NOT use pre-written adventures. Write up a quick and simple adventure and use that to test. Absolutely avoid using KOTS, because I suspect a major part of my gripe with 4E is that I'm stuck in KOTS with no forseeable end to the drudgery.