I think season 2 is not only about the bus crash. Obviously it is the backbone of the season and it is going to be the end game, but next to that, this season deals with the fallout from season 1's revelations and happenings.
This episode is a prime example of that: the episode's "higher goal" is to investigate the bus crash but during that, lots of things are happening.
I loved this episode, and that would be the first reason. Loved the amount of season 1 elements. Clarence Wiedman, Aaron Echolls, Abel Koontz... they were awesome. I especially loved Logan being locked up with Aaron - it was bound to happen, and it finally did. I found it somewhat surprising that Aaron still claims that he didn't kill Lily. And even more surprising that he believes he has a strong case - that he will find a way out of the prison.
Clarence's involvment was great. Abel appearing at Veronica's at the beginning of the episode was unforeseen and I liked that storyline alot. It started off like any other favour Veronica would do for a random person but ended up being rather dark and twisted - the definition of noir. You mix that with the teen drama and you get classic Veronica Mars.
Plenty of other things happened too. Keith losing the election while wasn't a surprise it wasn't set up as one(it happened right at the beginning); after the previous episode it was obvious. Keith is not willing to get his hands dirty,whereas Lamb is. Cliff doing Veronica a favor infront of Logan = win. Also, featuring Joss Whedon.... win. Veronica faking a photo gallery picture for his father... win. And really, there were lots of small moments like that.
The occasional comic relief was great in this episode, so was the rest of it; by the end I did feel sorry for Abel Koontz and it really felt that the plot progressed alot; with style. Bottomline is that I loved this episode, "exactly why I watch this show".