Currently AROS is available in a quite usable state as native and hosted (under Linux, FreeBSD and NetBSD) for the i386 architecture (ie. IBM PC AT compatible clones) and hosted (Linux and NetBSD) for the m68k architecture (eg. the Amiga, Atari and Macintosh). There are ports under way at varying degrees of completeness to SUN SPARC (hosted under Solaris) and Palm compatible handhelds (native)."
I would not call it useable for the average user just yet, since it seem to lack most software. So far it seems to be only interesting to those people who would want develope software for it or for those who just want to see how the gui works. Atleast that seemed to be the case when i tried it out a few months ago.
I must say i find the system itself impressive, as it seems the share the responsiveness of the orginal amigaos. I look forward to the day when more software and drivers are avaliable.
I only have experience with the x86 port though..
I am sure this will change once some more software has been ported.. :-)