barry's point is easy to see and it's actually true, but I think it's not a matter of bias in the sense of a "conspiracy". It has more to do with reviewers - people, in general - to be well aware of the 3DS limitations, but not so much of Vita's. 3DS ports are botched? " Yeah, but you'll have to take into account 3DS' limitations" -> 87 metacritic
Borderlands 2 port(a UE3 open world game which runs like shit on PS360 too) is botched? Buh, bad port, Iron Galaxy is shit, 64 metacritic
You don't have to take the names of the reviewers to prove this, the general consensus and the metascore is enough to see that the two games(but you could also get other examples) have been treated differently. Again, this has nothing to do with any obscure conspiracy, it's just that people think that Vita is capable of some incredible shit.