Ha, I caught it for a few bucks at a discount theatre on vacation this past weekend as well.
I liked it--conventional, but generally pretty well-made and solidly acted--but looking back on it, I can see what you mean about the prosecution. My gut feeling is that the "opposing side," as it were, was written (at least for the screen, and probably with less subtley than the novel) to be somewhat ineffectual so Haller looks much better by comparison. But that's a guess more than anything. I'm not a lawyer, nor do I generally read too many legal thrillers, so I'm no expert.
I'm guessing the novel gave more insight as to why the prosecution did what they did. I don't read many legal thrillers either, but I've seen enough legal TV shows to know the prosecution was asleep at the wheel.
I did enjoy the movie a lot, loved the story, loved the acting, loved the gritty shot of Los Angeles, but it would have been more suspenseful if the prosecution could have been able to throw up a road block or two along the way.
I haven't gotten to my signed copy as yet. I'm holding out on the movie until I read the book as well.
I do know, though, that Connelly wasn't a fan of the Bloodwork adaptation by Clint Eastwood, but he did think the Lincoln Lawyer was done justice (pun intended, unless it was lame, in which case it was accidental). Eventually the interview will be on SlowTV, as they filmed a number of things at the Sydney Writers' Festival.