I'm not sure if "two-and a half" was intended as a length or a rating; assuming the former, I can understand entirely. I enjoy Goa, but it's a one hour game, maybe 75 minutes if teaching. At 2+ hours, yes, it's dull.
I also don't look at the auctions as being the driving mechanism of the game - if they felt that way to me, it wouldn't be a game I cared for much. (For me, the auctions feel similar to those in Outpost - important, but you can't win the game by focusing on auctions no matter how well you do with them.)
Not that it's a reason for you to spend more time on Goa, but it is quite interesting with two players, a fact which surprised me.
Oops. That was meant to be two-and-a-half hours. Fixed.
I've never tried it with just two players. Maybe I should.