Certainly not "just as good", but not entirely useless, either. The main thing missing from it vs a real Beeb is video output. I corresponded with sprow once about that, and he indicated that adding it would be "possible", but he has no interest in doing it himself.
Yes, they do look interesting. I'm planning to buy a couple for poking at when I have a functional workshop again.
Check out Minix. It's an OS designed to be part of an educational course in OS design (and, incidentally, the precursor to Unix). The course books (by Andrew Tannenbaum) are available - if not free/online, at least via Amazon & ebay. And they are highly recommended by people who appear to know what they're talking about.
Speaking of which, I wonder if anyone's ported it to the R-Pi yet? If not, it could be an interesting project; one that could be tackled a step at a time, using the existing Minix courseware and the R-Pi Foundation's docs.
HAH! *fistbump*
Lately, I've been trying to rein in my brainfarts by writing them down someplace, forgetting about them, and getting back to the "having a functional workshop again" project with will, in theory, make all the other projects possible. Though even that has been severely backburnered due to Life and Stuff[tm].
PiXi-200 is a cheapish FPGA addon/piggyback board for the R-Pi.