I think for me the biggest attraction about carputer is that flexibility.
1. Wifi, autosync musics/videos, having a large library.
2. GPS map updates
3. Mostly a fun hobby, expensive at times, and lots of headaches too.
otherwise other units are quite up to par with carputer in terms of features, and a lot less headache, but keep in mind that factory units are usually around $2000, for that price, you can build one wicked carputer setup.