My first keyboard was a Casio CTK-650 keyboard. Indeed it got me started, but it wasn't very satisfying. I only remember ONE good sound (a synth-string performance sound). The keys were very bad, they rattled extremely after two weeks. And the internal speakers were very weak, too. A few month later I bought a Yamaha SY-35 synthesizer. That was something better!
I would take the Yamaha, too!