The other day I decided to download the Cinnamon engine and try it out in my Fritz 12 GUI just to see if it played a reasonable game and could it be used to practice against. It does and it can. It's rated 2031 on the CCLR 40/40 list.
The below game was a casual one which I played while my wife was watching the Lifetime Movie network which carries movies aimed at women; usually they end up murdering their husbands or their kids are kidnapped, or some such. As you can see, the engine actually seems like a good one to practice against because it's not so strong that you can't defeat it and at the same time if does not seem to make gross tactical errors then play like Grandmaster. In this game it made some small positional errors and only one tactical error (at move 33), so it plays very much like a reasonably strong human might.