SPOILERS people.
I don't understand where the B+ rating is coming from, Bob. Maybe I just didn't do a good job of keeping things in perspective, but my reaction to Tron has a lot in common with your reaction to Transformers 2.
Maybe I'm just getting old; maybe law school has crushed the childlike hyper-enthusiasm over anything dressed up in sci-fi colors right out of my soul. Maybe an upbringing that revolved entirely around Star Trek set my standards too high. One way or another, I've lost patience with films that have less ambition than the average tuna fish.
The work by Daft Punk was solid. The light cycle animation was solid. But those two things only serve to make the movie bearable. Tron Legacy is prevented from being "good," or from even approaching "good" by the formula story.
The formula story isn't by itself the kiss of death; everybody uses it these days for pretty much everything, and considering the sheer quantity of films that Hollywood-types put out every year it would be unfair to expect them to reinvent the wheel every time. But there's good formula-story work and bad formula-story work. This was bad formula-story work. The characters were paper thin and the plot kept going out of its way to do things that made no sense or had no relevance to the story. Transformers made you angry because given all the potential of the big-robots-from-machine-planets idea, it seemed absurd for the plot to expect the audience to be more interested in some unlikable kid's sex life. Tron pisses me off for pretty much the exact same reason. Why are we supposed to care about this kid, exactly? I don't even remember his name; I think it might have been Sam, but maybe that was the kid from Transformers. Maybe they're both Sam. Whatever the case, he's a jerk who wastes his life and is crippled by his daddy issues. Why would I want to watch a movie about him? Given that the girl-person never says or does anything, why am I supposed to care about his relationship with her? Why is Encom evil, except for the fact that it's a big company? And how has the grid managed to exist for 20 years, given that it presumably depends on hardware that would critically degrade during that period? How did the kid manage to drive back to the city on a motorcycle when the whole point on the non-city environment was that it was accessible only to of-road vehicles? Why did Clue go all the way to Flynn's lair if all he was going to do was turn around and go back to the city, and what exactly did he get so angry about while he was there staring at the knickknacks? What's the deal with Tron? If he was repurposed to be evil, then why do we care about him? I mean, if all he is is a mindless minion doing what Clue programmed him to do, then he's not really a character, is he? He's just a thing.
The biggest offense is the new back story. The grid produced an entirely new race of digital beings. These beings, somehow, had the potential to change the human world. And then they were all murdered by Clue in an act of genocide. Let's ignore for a moment the insane lack of specificity with which its suggested that these beings could change the world. The idea of a whole new species evolving on the grid is a HUGE, AWESOME, big-idea sci-fi concept. It's the sort of concept you could use for an entire stand-alone trilogy. But this film just uses the idea as an excuse to have a long chase scene and give otherwise uninteresting characters some sense of seriousness. Why is the bad guy bad? Uh, um, because he committed genocide. Yeah, great idea! What CRAP! That's the sort of bad formula-story work that we saw in the 2nd Pirates movie. Why is Davey Jones evil? Because, um, uhh...something about some woman who scorned him or something. Alright, great! Now we can get on with the formula story!
Every movie is going to be limited in some way by some degree of formula-story telling. That's just reality and there's nothing wrong with it. But just because you're bound by a formula story doesn't mean that every character has to be boring or that every plot point has to be either predictable or nonsensical. And this reality is by no means a license to develop really big ideas and then throw them away in a five-minute back story sequence just so that you can get on with the flashy effects and daddy issues.