It'll sound fine through an amp. In fact, you probably need to put it through an amp to get the best out of some of the effects.

The keys aren't as "positive" as, say, my son's Korg 800 synth, but pretty good for plastic. No bend or mod wheels on it, but I suspect you're not too worried about those!

Reverb and flanger effects are good, but the chorus effect is a bit disappointing. Trumpet, guitar and violin effects are nice but the flute effect's a bit crappy.

all in all, though, a bargain for the price.