Does anyone have one of these?
I'm close to buying one for $35 off of craigslist. I think it would be a nice little thing to start getting into synthesizers with.

If you have one, is it hard to hook up with a piano or guitar through an amplifier?

Don't do it. You can't really play the "keys" since it's so small. Only really useful for making obnoxious noises.

It's a fun little toy, if you view it as such. I say get it and have fun, but don't be surprised if you don't end up keeping it for a long time. I think we've all spent 35 bucks on worse things though, right?
Telecasters-->Dunlop Volume Pedal-T1M Pearl-AMT Japanese Girl Wah-Line 6 M9-Ibanez DE7-EHX Cathedral-->Mesa Boogie Nomad 4x10 combo