I was very happy with my Fable II purchase at even high release pricing. On the other hand, something like Halo 3 just became a glorified door-stopper very quickly.
It will all be up to your preferences in games, and what you feel like playing now. I absolutely loooove my RPG's, and buy most rated over 75%, but sometimes even a AAA RPG will not satisfy me when I need an action fix.
Here is another example. I like 3rd person action type titles along the lines of God of War, Devil May Cry and such, but I NEVER play them through a second time, I feel no compulsion to. However with RPG's, often they get a 2nd playthrough.
So it is all up to your discretion ^_^