Vega is probably better than Jacob and Kaidan but still stupid because given how the squad size was shrunk he takes away a valuable spot from a potential alien character, or even an ME 2 character.
He's definitely better than Jacob and Kaidan, but he still sucks. The only interesting bit that came out of him being in the party is him being a subject of Javik's mocking, and to see that, you had to pay money.