Cadash is a wonderful game and I would say it is likely the best two-player experience on the TG16. There are few games that my non-retro gaming friends will play, but this is one of them.
The great thing about Cadash is variety, as you can essentially play the game many different ways. First of all, there is the grinding people have talked about. If you want to just have an easy romp through the game, I think of grinding almost like playing an "easy mode." If you want to have an actual challenge, just make a go of the game, no grinding.
The Priestess / Ninja combo makes this game cake and this is what my friend and I usually will play. The Fighter isn't too bad either, and I have completed the game with him too. I honestly don't think I have ever beat the game with the Mage before, so maybe that will be my challenge this weekend (aka - probably not).