You know, I've been seeing too many glum threads lately. I hope this thread will perk people up! Tell us all what you love about Spiral Knights!
Me? Oh, I like that it's native to Linux, for one thing. Sure, a lot of games are doing this lately, but this was one of the earliest commercial "Play on Linux" games that I had known about. It has a special place for me!
I also like the deceptively simple modeling style. The only way I can put this is that you have to give it a try before you understand what I mean. (No, I'm not doing models anymore. It's really not my thing; I'm more comfortable with 2D sprites.)
And the music is cool. 'Nuff said.
I like that you can trick a Trojan into killing it's own Monster allies.