While it has a few notable problems, Sonic 4: Episode 1 is a decent throwback and a solid step in the right direction.
The story is simple, which is exactly how it should be. The story doesn't bog you down with Sonic attempting to get funky with a human or any of that pointless fluff. It's just the simple concept of Sonic trying to hunt down Eggman (or Robotnik for those of you who are slaves to nostalgia) and destroying his crazy machines whilst speeding through a set of well-designed levels.
The graphics are very pleasing to the eye. They colorful, detailed, and look very nice. The soundtrack is pretty good too. The soundtrack is very 16-bit esque and somewhat brings back that classic feel of the Genesis classics.
The levels are, for the most part, fairly well designed. They consist of that high-speed Sonic goodness we know and love and combine it with solid platforming. When you play the first level, you'll notice that the physics feel a bit strange at first, but you'll get used to them after the first couple of stages. I did have a few nitpicks about the level designs themselves, however. For the most part, the level designs lack any serious challenges, and the game is overall pretty easy. There are a few moments that will attempt challenge you, but those moments are more frustrating and annoying than anything else to be honest, and aside from the final boss fight, this game is fairly easy.
A problem worth noting about this game is that it's very over-priced. There are only around twelve levels, and you can easily beat this game in a single-sitting, and it's going to cost you $15. If you have an iTouch or iPhone, get it on that to save yourself a few bucks.
All in all, Sonic 4: Episode 1 is worth getting for Sonic fans who have been wanting to play a Sonic game that manages to escape mediocrity, and I'd definitely recommend it; just be ready to pay more than you'd like, and don't expect to be challenged too often.