On those terms, this sequel doesn't disappoint: the primary car sequence was sufficient to have me laughing out loud at the sheer improbability of it, there are some good fight sequences, and Stratham frowns his way through the entire affair. It didn't work as well as the first time around, though.
For the plot, they've changed the emphasis. Here, he's being a good guy through choice. Before, it was very grudgingly. And they've raised the stakes from being personal to far more apocalyptic level. There's a kid (never a good idea), and there's a sort of love interest which - thankfully - doesn't go anywhere.
The fight sequences make a vague nod towards justification by having a line of dialogue about why everyone's stopped shooting just before the pick-a-number battle, but they don't come close to the oil fight of the first movie.
My biggest complaint is that the Psycho Lieutenant is a skinny blonde who never appears wearing anything more than panda-eyes make-up and underwear. Really. I know it's hot in Miami, but still.
That's probably the reason for all this, by the way. The first film was a Canal+ production, set in rural France. Now that it's successful, we relocate to Miami, and the somewhat-grey morals change to more heroic levels.
It's still enjoyable. It's excellent mindless action fun, and I'll be buying this when it comes out. Stratham does his job well, and the character of Frank, with his rules, his car and his concern for his suit are all great. It's just not as good as the first film.
Mind you, what I'd really like to see is for Besson to produce a cross-over movie between this and Taxi... (and I mean the original, not the Queen Latifah version)