I'm not a keyboard player, but I needed one to use other sounds (guitar, strings, organs, etc) in my recordings. I was looking for something cheap, compact and good quality. I was in between a CTS200 (because of the colours), the CTX700 (because of other comments and reviews. It's so ugly though!) and this one. At the end the CTS300 won because of size, portability and sensitive keys (compared to CTS200). The sound is more than ok for an eternal amateur like me. My favourite thing is the small amount of buttons since it has only 9 (not counting power and volume) so it is really easy to use. Just plug it and play! It has a really handy control wheel that allows you to move in between sounds. It also has a pitch wheel which I don't use much particularly.
The quality is OK, but the feeling of the keys is too plastic. I'm not complaining though.
Pros: size, portability, low amount of controls, sensitive keys
Cons: Not many to mention, just the plastic feeling.
In my opinion, if you are an amateur like me, get this one. The CTS200 is tempting but CTS300 has sensitive keys.