Almost any project is a good one. You say "only" 5x5", but what you wanted to put on it would fit on a board considerably smaller if you really wanted it to be compact. In fact you could get more from a single IC if you want to use the 65c134 65c02-based microcontroller-- more speed, more RAM, more I/O, etc..
My own workbench computer can be seen at
http://www.6502.org/users/garth/projects.php?project=1 (although the pictures and info there are rather out of date, since I have added quite a few very significant features). That board is 4.5"x6.5" and has 3 65c22's, 3 65c51's, 32KB of EPROM, 16KB of RAM, a keypad and display with a connector for additional remote ones, fast A/D and D/A converters with 3.5mm phone jacks for audio in and out and sockets for anti-aliasing filters, an I²C port on the front, a connector for a separate frequency/event counter, printer and RS-232 ports, MIDI, a port for a modem and a socket for a plug-in wireless link, and sockets for a mezzanine board which is not built up yet. It didn't have all this to start, but it grew over the years. I've used it for scores of projects-- both work and hobby-- since 1992.
No matter what you do, you'll learn what might have been better. You can't always wait until your design is optimium though, because it will never get there. Whatever level you're at, you'll figure out something better in the process and wish you could start over. Enjoy the process, and enjoy the results.