RealAtrus

@moroboshi
Dear moronoshi, Sonic Generations for PC is available on Steam and it supports glorious 120fps. Hope your eyes won't explode from that awesomeness.

@foxhound
I don't usually nitpick a list, but I'll make an exception for you.
Your list contains mainly spin-offs. That's like citing Dr. Mario, Mario Is Missing (argh, I remember that horror), Mario Party, Luigi's Mansion or whatever as proof that real Mario games suck. Not to mention Zelda CD-i...

Labyrinth and Drift, are you kidding me? Two ancient irrelevant handheld games that barely anyone played. Drift is definitely a spin-off - it's a racing game (Sonic in a car, OMG!).
Sonic R - spin-off. It was actually a rather nice racing game featuring Sonic characters (I played the PC version, never had a Saturn). And it has a cheesy soundtrack that is beloved by many.
Sonic Riders - spin-off. Also a good racing game. A bit difficult to get into, but once you know how to play, it's challenging and fun. The "Zero Gravity" sequel was not as good, I thought, but you'll undoubtedly find people who like it better than the first.
Secret Rings - spin-off (part of the hopefully cancelled "Storybook Series"), although it perhaps wasn't intended to be one, originally. Still, as weird and difficult as it was at times, I'd say it's one of the best early Wii titles.
Black Knight - spin-off, part 2 of the Wiimote-centric Storybook Series. Come on, if you expected this to play like a traditional Sonic game when it was openly advertised as a sequel of sorts to Secret Rings, then you deserved to be disappointed. People who took the game for what it was actually found some enjoyment in it.
Shadow - out of all spin-offs, this one plays most like a real Sonic game (namely Sonic Heroes). But it's a different character and relies on guns for defeating enemies (the usual homing attack has been nerfed to favor weapon usage). I thought it was a decent game, not great, but with some interesting and fun ideas. Certainly not as bad as many people think it is. Hey, GameTrailers gave Shadow a better score than Generations, what's up with that? ;)

Now, finally, the only two real Sonic games from your list: Sonic 2006 and Sonic 4.
2006 was terrible. The ultimate low point, no argument about that.
Sonic 4 E1... well, shouldn't have been called Sonic 4, as it does not live up to that name. But the game itself isn't that bad. Some hate it, others like it.

@Organic Jerk Do us a favor, stay silent some more. The game is not disappointing, this sorry excuse for a review is.

@Undulation
Yeah, and why not in crappy 320x224 pixels with 61 colors (plus a few more via some palette tricks)? But wait, as a European I want to play Sonic Generations with 50fps. Interlaced, of course, I want that retro feel. Blargh.

Yes yes, 60fps are better than 30 (and 120 better than 60). We all know it, no point in constantly repeating it. But 30fps aren't as bad as you whiners claim.

@biglozbowski Nope, it's a shitty comment. If Ludwig is a cynical old fanboy who thinks Sonic died after the Genesis era, then he should say so without resorting to wannabe clever analogies. So that even the last person can see that his review is BS.
Just a reminder: There are many younger players out there who started playing Sonic games only at the Dreamcast/GameCube era. Sonic Generations must be like a three-disc Michael Jackson Greatest Hits album, featuring one disc of pre-natal silence.
Har har.

@Undulation The framerate isn't crappy. It's a stable 30fps with very rare dips in certain places. Take the first level, for example, 30fps all the time except for two instances:
http://www.youtube.com/watch?v=JlBE8DHXSQw
(Splashing water after the robo fish chase and breaking a bridge for a shortcut, which this player doesn't do.)

Nobody has the PC version yet, but it will most likely run in 60fps - if your PC is good enough.

@PointlessPuppies Only retro whiners ("Sonic was only good on Genesis!") who love love classic Sonic and detest modern Sonic love it for the nostalgia. Ludwig seems to be such a pitiful person.
Others love it for featuring two good gameplay styles (yes, many people actually like modern Sonic's gameplay better), great level design and excellent music. And a bit of nostalgia.

Point is: if you liked the daytime gameplay in Unleashed HD and Sonic Colors, then you'll have fun with Generations. With or without nostalgic feelings.

@MW49350 Every single Sonic game? Wrong. Sonic Colors was a retail game that was not weighed down by its gimmick.

@legacybush There is no cycle, only 2006.

Of course you could pre-order games during the Genesis era. I remember doing so with Sonic 2.