I absolutley love this game. Many consider it the best sonic game ever. But i'll be honest, this PC port of the game is horrible. There are bugs EVERYWHERE.
I'll start with the Resolution. a recent update allows you to change the resolution beyond 720p. This sounds great, but it actually breaks many graphics. Mostly with the UI and HUD. Some things will appear WAY too small and sometimes even appears in the wrong area. Even worse though there are flickering and even spazzing glitches that happen regardless of the resolution. Graphics aren't the only problem tough.
Many sounds are also broken. Sometimes a sound won't play, even worse sometimes a sound won't STOP playing. I've especially had this issue in the chao garden when a chao goes swiming. Even when i get them out of the water the spashing sound plays on an endless loop. Twinkle park has volume issues as well. A lot of noises are either too loud or too quiet. You often can't even hear the music.
I've heard this game has slowdown issues as well, i haven't really had a problem, but maybe that's because i have a pretty good PC. But a heads up just in case.
Overall this really feels like a shoddy emulation rather than a true port. If you've played this game before and want a little nostalgia, you may be willing to handle it. But if you haven't played it before, i say skip it.