[lgl]

Sure, but can we really deny that the 5 star rating is pretty decent and simple, having an exact middle point and then two levels for each side.

[magicalhippo]

Well yeah, but I feel the neutral midpoint is problematic because I feel it's too easy to pick it. Removing the midpoint forces one to decide which side it leans towards.

If one really feels the need for the "meh" category, I'd say go for a 3-level system: bad, meh, great.