Borderlands 2 was a bona fide hit for developer Gearbox Software, selling millions of copies on PS3, Xbox 360, and PC. In fact, it was so popular that Gearbox and publisher 2K agreed to let Sony help bring it over to PlayStation Vita, a great sign for a struggling handheld with only one good first-person shooter to its name ( Guerrilla Cambridge’s Killzone: Mercenary ).

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“ The game ran somewhat sluggishly, held back by a subpar framerate, and it even froze in place a couple of times for a second or two...

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“ There’s simply no good alternative to a good old-fashioned button, whether it’s on the front touch screen or the back touch pad.

It came as a surprise to find Borderlands 2’s PS Vita iteration at the PlayStation GDC booth, especially because Sony, 2K, and Gearbox have been so mum about it. Running on debug Vita hardware, Borderlands 2 looks the part – and is reportedly content complete with some DLC added in -- but it’s definitely not on the same level as its console and PC counterparts. (It can, however, speak to the PS3 version of the game with Cross-Save.)In the five minutes or so I spent with the game, running around a couple of areas while gunning down enemies, I was disappointed that Borderlands 2 isn’t running better. It’s not a major surprise that there are some performance issues – PS Vita is powerful, but not as powerful as the PlayStation 3 – and I couldn’t help but wonder if Sony and the studio responsible for the port, Iron Galaxy, are working on further optimization.My biggest qualm during my brief time with the game, however, was its control scheme, or at least portions of it. Because of the fact that Vita lacks R2 and L2 functionality, and because its analog sticks aren’t clickable (therefore providing L3 and R3 mapping options), developers have attempted solutions – some more clever than others – that strive to mitigate the loss of four buttons. Some of Borderlands 2’s solutions, unfortunately, don’t seem to be very good ones, even if there’s seemingly no better option available.Not surprisingly, aiming and shooting are mapped to the Vita’s L and R buttons, respectively, and the face buttons allow you to reload, jump, and do all the rest. But to squeeze in Borderland 2’s robust set of features, four essential actions have been mapped to the touch screen and back touch pad.The left side of the touch screen activates your character’s special skill, while the right side of the touch screen tosses a grenade. These decisions aren’t necessarily questionable – indeed, chucking explosives with the touch screen is borrowed from the failed Vita shooter Resistance: Burning Skies – but when the back touch pad gets involved, things start to fall apart a bit.There’s simply no good alternative to a good old-fashioned button, whether it’s on the front touch screen or the back touch pad. Then again, I only spent a few minutes with it; maybe it’ll be easier to play and make more sense when I dig in and play it for hours instead of moments.Borderlands 2 is scheduled to come to PS Vita this spring alongside an all-new model of PS Vita . For more on both, check back with IGN.

Colin Moriarty is IGN’s Senior Editor. You can follow him on Twitter.