Just finished the finale. It was fairly effective, but it had some logic holes. Mainly, given how Ben's changes take effect in real time in the present (as we saw in the climax here), then how could Gideon Rydge have existed to build the quantum chip to find Ben before he ever met Hannah? If Jeffrey/Gideon's entire rise to wealth and power was in reaction to Ben's actions and the stock tips Ben provided, then he shouldn't have been "butterfly-effected" into existence until after the firefighter episode. And would Jeffrey even have been born if Ben hadn't encouraged Hannah to go to college, then helped advance her career? Without him, she might've been stuck in that small town as a waitress forever and never even met Joshua. So having him be around since the start of the season just doesn't make sense by the show's own fanciful temporal logic. They're trying to have it both ways and do a closed-loop story within a mutable-timeline series, and that's self-contradictory.
Also, while it's nice to see the show finally, finally make at least a cursory acknowledgment of the effect of Ben's changes on the present and why they don't affect the team (the "quantum bubble" protecting them), the way the history rewrite was depicted in the climax, with the wind machines and sparks and rising glow and holding hands, seems a bit much. I mean, is that what everyone in the world outside the Project experiences every time Ben changes the past? Or was that just a side effect of the "quantum bubble" breaking down?
I was going to ask why Ben didn't save the race car driver first and then go deal with Jeffrey, but it just now hit me that it's because he would've leapt and lost his chance if he hadn't dealt with Jeffrey first. That went pretty much how I expected -- I knew Ben wouldn't smash his computer and would find a way to win Jeffrey over with words. I didn't expect that he'd do it by showing Jeffrey what it was like to help someone, and I really liked that. (Although it relied on TV and movies' perpetual misunderstanding of how defibrillators work, reducing them to a magic on/off switch for hearts.)
The quote of Mike Post's theme to the original Quantum Leap under Janis's explanation of how she owes her existence to Sam was a nice touch.
The ending was unexpected. If the show gets a third season, I wonder if it'll be a permanent status quo or just a single-episode thing like that time Sam and Al swapped places. I can see it going either way, or being a limited arc. I wouldn't mind seeing a season where Addison's the leaper and Ben's the hologram, though I doubt they'd actually do that.
If they're both leaping together for any length of time, I think Magic should be the hologram, since Ian and Jen would be needed for their own tasks, and giving Ernie Hudson more to do is never a bad thing. Although I liked it when they got to take turns hologramming late last season and early this season, so I'd like to see that continue.
EDIT: And yes, it just struck me how appropriate it was that I ended up watching the Quantum Leap finale on February 29.