It's a good game that never really borders on great.
The gameplay is fun, the visuals are some of the best seen on any console, the story is interesting enough to give the game's progress meaning and the sandbox/open world gives the game a medieval GTA style experience. It's just too bad that the game suffers from a serious case of 'Been there, done that'. You will replay the same missions over and over again, encounter the same people and basically just undergo the rinse and repeat exercise to ad nauseum.
The unskipable interactive "cut scenes" make this game drag on a lot more than it should. Often fairly long, they are rarely entertaining and really drag down the experience. It comes to a point when you dread certain aspects of the game because you know a 5 minute bore fest awaits.
I would recommend renting it, but when it eventually goes down to $20-25 it is likely worth a purchase. I think the game has great potential, and with the great sales the inevitable sequel could be one to watch if they build on the good foundations and cut out the repetitiveness of the original.