It's just a straight port of ppp-1.1. It works with NeXTStep 2.1. It is based on the BSD part of ppp-1.1, but with header compression integrated. I have only tried MacPPP running against it, but telnet, eudora, and GopherApp all work fine. FTP does not work at 2400bps, but does at 9600.
Initial reports are that it is fairly solid.
Simply stated, Joe Blow can use this software at home, but commercial PPP providers can not use this software for their exploitation without written agreement from the authors. There are reports that it is difficult to get it to compile on 3.2, and after you succeed, it doesn't work, as some system calls are missing. The reports about it being difficult to compile aren't true. These people simply haven't read the readme's. The PPP-2.2 package implements BSD packet compression.