does

count? :3
Other than that, just having all of the core functionality the game has, being easy to setup and having some decent themes is all I need to consider a simulator good.
Be-Pachi has most of what I'd want in a good simulator right now. The only things missing that I wish it also had would be: more themes (red and happy sky would be nice), showing BPM as part of the song information, song previews, score tracking, videos working and maybe a few more less important cosmetic details. Mostly things that really would be nice, but don't actually break the game if they're not there.
The
ideal simulator would be a whole different ballgame though. An
ideal simulator should be able to do pretty much anything the game can in terms of gameplay, and then some extra on top of that (i.e. if you have the program on your computer, you can do stuff the game doesn't actually do, like add however many themes you want, download and play unofficial songs, add extra options the game doesn't have, etc. etc.). I don't really mind at all if whoever is making it decides they want to take it in a completely different direction (like making a beat-puzzle game), but it absolutely must have the basic "normal" game also available for me to actually consider it a good simulator.