The Yamagi Q2 looks good, but it's a little unclear to me what the difference is between this and icculus. Apart from 500 typos (uhh, that's pretty crazy).
In practice, it doesn't seem much different. It plays as usual, really. Also, Yamagi apparently removed the software renderer, but in multiple places there's still mention of it. It's unclear how to build that.
Bottom line, what I mean to say is, is there a point with this port? Apart from being a cleaned up (and amputated) icculus Q2 source?
I don't know, I just never really had a problem with Icculus Q2. For singleplayer, I'll take icculus any day. It seems to work fine, and gives me the most options when compiling (ie it's the most complete port).
If you want a more modern Q2 port, you can't beat QuDos' stuff.
http://qudos.quakedev.com/