Okay, and I lied. I do have a different complaint. I managed to get all the way to the Death Egg, but when I started that level, I got hit with an insane amount of slowdown, to where I couldn't really play it. It was like a 2-D version of Sonic Labyrinth, but slower. Is that just my computer, or is the last set of levels that resource-heavy?
Other than that, I've loved the entire game from start to finish. (or at least up until Death Egg, obviously) The levels were pretty good, if not a little oddly long. Well, maybe "long" is the wrong word, but many levels have multiple stretches where nothing happens and it's just a straightforward run on some bumpy ground, and it gives a feeling that the level's about to end. However, once you get into your mind to look for the signpost, you suddenly start another stretch of the level. That was probably my problem with the signposts and the bonus stages. If you don't want to change the behavior after hitting the signpost, maybe you could put a sign up shortly before it to say that the end of the level is coming up, like Sonic CD did.
Also, what made you decide to give eyes to all of Robotnik's ships? They were fun bosses, and I enjoyed nearly every single one, but I always ended up wondering why they had eyes when they didn't in every other Sonic game.