Sonic has had a hard knock life ever since his heyday on the Genesis. He had a ton of problems transitioning into 3D (which most people say the Sonic games never really pulled off well), he's been held back by stupid sidekicks, his old games have been shoddily ported to every platform imaginable, his new games have been riddled with gimmicks, and he's even been subjected to bestiality. Eww.
I'm not going to go into detail as to why Sonic has sucked, but I'll summarize most of it in once sentence.
"The core ideas that made Sonic fun in the first place didn't translate well into 3D."
With that said, the Internet is losing it after Sega just announced the upcoming release of Sonic the Hedgehog 4: Episode 1, which returns to the classic Sonic-only 2D style that popularized the hedgehog in the first place.
Image from Kotaku
Sonic the Hedgehog 4 doesn't guarantee us much of anything, other than it being a 2D Sonic game that will be downloadable in episodic form. It could still suck. It could still feature some of the elements that made the more recent Sonic games awful. But I am glad to see Sega finally care about the people it makes games for and at least attempt to create a product with them in mind. Will Sonic rise to prominence on par with Mario like he did back in the early 90s? Maybe that's a bit much to ask. Let's see if we can get a good Sonic game first, then we'll talk.