Guh, I always forget about the "new beams are upgrades" thing. That really bugged me about three, a lot. I like the array of weapons. Plus, I think that Prime Trilogy showed how beam control could have been handled excellently, using the Wiimote.The controls are different, the most obvious being that there's no way to switch between beams - new beams are upgrades rather than options. Though the new controls fix the problem you were having with the bosses - because you have to aim manually, there is more skill involved than just 'lock on and spam the A button'.
Personally, I loved 3 - better than 1, I think, and 2 is a bit odd.
Anyway, zero, in my opinion it's all downhill from Prime. Echoes has some problems where backtracking takes forever, although it is definitely still a really, really good game. Corruption takes advantage of slightly better hardware, but there's a significantly less exploration than there is the previous two games, mostly due to valid complaints made about the previous game.
I generally rank them 1 -> 3 -> 2, but they're still all extremely good games. I've been considering replaying them again recently.
