The music is pretty good yeah.
I still haven't played or bought the second game. From what I've gathered it's not nearly as good, so I'm waiting for a big sale or an inclusion in a monthly bundle.
Eh, it's sort of hard to pin down. I don't know if I'd call it "bad", and if the first Hotline Miami didn't exist, I'm sure that people would have loved it just fine, but yeah, I just didn't enjoy it as much as the first game.
The common complaint is that the levels design leans more towards large open areas as opposed to the sequences of smaller rooms in the original. This gives the game a wholly different feel, and not in a good way. Instead of the "burst in a room, murder some guys, take a breath, repeat" rhythm, it's more "spend a lot of time using the zoom feature to scope out the far corners of the room to make sure you won't get blown away as soon as you walk too close to someone you didn't even see a second ago".
This also ends up putting way too much emphasis on the ranged weapons, which honestly was never HM's strength. In the first game, the ranged weapons always felt like the thing you'd use as a last resort or in certain situations, as they'd often bring the entire level's worth of bad guys running. While I'm sure it's possible to beat most of HM2 with melee weapons, it doesn't feel nearly as doable.
Not only that, but there's the attempt to shoehorn way more of a story into the game. Now, I consider myself somewhat observant. I never really have an issue following the plots of the more "confusing" movies out there (except Primer... one of these days I'll figure out what the hell happened at the end of Primer), but there was a LOT of HM2's plot that I found to be intentionally obscure. It doesn't help that you only see a lot of the characters from above, so there's a lot of times where I wasn't even sure who's supposed to be who in the cinematics. After beating the game I went online and looked up a plot summary, and yes, while all the details were somewhat there, there's still no way I would have put all that together by myself.
Still, for all the negatives, I can't say I'd avoid it completely. The soundtrack is still
fucking awesome, and there are still plenty of memorable moments and great levels. The last level especially takes some... interesting.. turns.