I paid full price for Alpha Protocol. Don't regret it for a second. Despite the slightly clunky controls and set-pieces at times, I'd still rate it one of the best games I've played in the past few years. The majority of the hate is due to reviewers who were expecting "Mass Effect 2 as a spy".
I don't know if NFS: Hot Pursuit is average, but I was certainly gravely disappointed with it. Definitely lacking compared to the series up to that point... minus the disgrace that was Carbon, of course.
Mirror's Edge is another one. I understand why it got hammered in reviews, but it was still awesome for the things it actually got right.
I also recently played Homefront, which I saw got a number of fairly "average" reviews (at least in the "7/10 is bad" review world in which we live). The single player campaign has appalling writing/acting and is even shorter than MW2, but I have to say I found it significantly more enjoyable.