Mai is pretty awesome. You can clearly see some normals from other characters in her move set, but she's fun as hell and being able to do her special moves is a blast. It's just too bad that the netcode in DOA isn't up to par with everything else. Even KOF plays great online now.
Mai herself only has her main outfit in red and blue. That's it...nothing to unlock. If you want more outfits, you have to buy them. She also has no English voice.
Note on the PC version- it's not very good. The only reason I've even been playing it lately is because it actually runs well on my Surface Pro 4, and it's cool to have a 'portable' version of the game again.
I tried to play online on PC, which is far worse than the console versions, and only got one match. Dude picked the training stage and tried to run away...but this didn't work since I could just throw fans at him. He rage quit after several minutes of this, lmao.