Honestly, I'm not a hard guy to please, but I agree that naming it "Sonic 4" kind of has me paranoid of it not living up to it's prequels. I haven't really played any Sonic games that were downright horrible; Shadow the Hedgehog and Heroes were the most recent (console) Sonic games I've played, and the only real gripe I have with the games are the somewhat unforgiving level designs. Heck, given the fact that I have a Wii now, I have half a mind to go pick up Sonic and the Black Knight; from what some of you guys are saying, it actually sounds pretty good!
You see, something that Ive seen many fans of anything, (sonic or Megaman, and not all of them, mind you- some-) cant seem to grasp, is the concept of a flawed game being fun.
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X6,etc.
This. I don't own X7, but from what I've played it didn't seem that bad. Aside from the whole "unlock X" nonsense, the game's perfectly playable, flaws aside. The reploid rescue thing was pretty messed up, though.
Also, I really don't see why people insist on giving X6 such harsh treatment. People go into it expecting it to play like it's past incarnations, and in doing so set themselves up to be shot down. A lot of gamers (Sonic fans especially)are simply closed-minded when they buy sequels, and it tends to shoot them in the foot.