Lupin isn't a class, it's a race. You did mention any race is available, as long as it has an LA of +0. Lupin, as a race, does not have a lot of powers. It's only ACTUAL power is it's Monstrous Humanoid type. Without that, it's actually less powerful than Half-Orcs.
It's got Darkvision, a non-automatic Scent that only works within 5ft, and bonuses on a handful of very specific things. I chose it because it's an anthropomorphic race with no level adjustment ('cause that's just what I like to play).