Best:
-Setting
-Looks nice*
-Highly team-based without personal score (meaning - all the score is team's score - counter example is, say, Battlefield which is basically team-based game but you have individual score)
-More knowledge-based than agility/reflex based
-The philosophy of game - everyone can use everything from the beginning, the classes only define the number of things you can grab
-Very good monetisation policy ("Pay-to-look-cool")
-Great maps (mostly), guns (mostly) and ships.
Worst:
*(I assume it looks even nicer when you don't have to play on lowest graphical settings because reasons and more reasons)
-All the technical stuff: dc's, lags, framedrops, the above and all that...stuff. I tend to say that GOIO is an indie game which tries really really hard to pretend it's not indie (and sometimes it works, sometimes it doesn't).
-Crazy King matches that take forever to end (or any longer than 20 minutes)
-Necessity to have all crew members play engineer (when playing competetively) in most cases. (or in general class balance)
-Too much of floating around, to little of fun (for example flying around on Canyons for 10 minutes and when you find enemy ship it turns out that it's metamidion and kills you in about a minute)
-Open "pan-like" maps that encourage sniping builds which are not fun at all mostly (I'm looking at you, Dunes!)
-Lousy, lousy tutorials.
-As someone mentioned - not much of matches are actually FUN-fun
-Around 50% time spent in the game is spent in the lobbies, waiting