Game-Breaker: A level 5 Alpha Combuster can shred through enemies and is so strong, you can make it the only weapon you need to get (give or take an Alpha Groovitron or Alpha Warmonger if you really need them). If you get the Infinite Ammo cheat, the Alpha Combuster is completely broken, overpowering enemies with More Dakka that never ends, ever.
Porting Disaster: Despite its lengthy delay, the Vita version features reduced graphical capability, has fewer multiplayer skins, is missing 2vs2 matches, and its main gimmick — crossplay with the PS3 version — is inexplicably cut.
It also has an unprofessional looking icon (streched out version of normal artwork) on the Vita home screen.
That One Achievement: The "Ironmadman" trophy. Over the course of your gameplay , you need to Hoverboot 112 miles, run 26.2 miles, and glide 2.4 miles. This trophy is tedious, and since there are Skill Points for Hoverbooting 100 miles, running 26.2 miles, and gliding 1 mile, for Hoverbooting and gliding, you won't even know how much more distance you have to cover, since it's not measured anywhere. The one saving grace is that the trophy combines distance covered between story mode and multiplayer mode, so even if you've finished the main game, you can still play online.
We're Still Relevant, Dammit!: FFA's use of memes as comedy can make it come off as this to some. Fortunately, that gimmick was dropped after this game.