After a couple of false starts, I finally finished the main quest this weekend.
A couple of spoiler-free thoughts:
1) I have to give Bethesda kudos for figuring out a way to keep the game going, even when you've "finished". Morrowind just kinda set you loose, with a "You rock. Go forth and be awesome". Oblivion didn't even go that far. There is still much to do in Skyrim (not just dungeon clearing) once the dragon issue is resolved.
2) Same thing goes for leveling. Once my character reaches "badass" status, I tend to lose interest (one-hit killing things is only fun for so long). However, in Skyrim, even if you max out your skills or hit the level cap, there are still Shouts to find/upgrade.
3) Perhaps this is a function of my impatient desire to wrap up the main quest, but much of the 2nd and 3rd act felt...less coherent than the beginning. One particularly important cutscene felt comic. The last hour or so had that whirlwind feel where you start to wonder if they're throwing a whole lot of stuff at you in an effort to distract you from plot holes or shoddy writing. It could be that there's a whole lot of context that I missed my first time through, but I kept thinking that in the end, Skyrim was turning into Oblivion, when it so wanted to be Morrowind.
Fun game though. I think I have at least a couple more playthroughs on the horizon.