Sonic has up and downs just like alot of series. Their a good games in the series and their are bad. Hell I would even argue that the good outweighs the bad (Mania, Generations, the Advance ones, DS ones, Colors, the classic games, Adventures, Heroes(that game if good, damnit), hell even the All star racing games are good.
Ironically i think the problem is Sonic Team, dissolve that team and get new leadership in their, cause they have been wildly inconsistent. It says something that the best one recently wasnt made by that team. I stopped reading the comics when they did a soft reboot, you know a series been going on too long when they do that.