I bought this one as an upgrade to my old CTK-601. I must say, I'm impressed. The reverb might not be as deep as the CTK-601, but it still works fine.
It has several key features, such as the ability to layer sounds (including pre-layered sounds), and spliting them at a key of your choice. It also has 10 DSP effects.
The piano sound is excelent, and sounds almost exactly like a real piano. The strings, brass, and woodwinds sound very realistic.
The display is awesome! It's backlit, shows a piano roll, a staff (treble and bass), temp, measures, meter, and other important info.
The sound quality is outstanding, outshining Roland and Yamaha keyboards easily. Definitly check out the ChurchOrgan (#019). In my opinion, it blows away even REAL church organs! The square, sawtooth, and other synth sounds are also, for lack of a better word, perfect. Definitly worth the buy!
Try hooking it up to a computer and playing midis with it. You'll be amazed, and almost frightened at the quality of it.
One thing that I couldn't do very well with my old CTK-601 was make recordings (for MP3's of my own songs). It was always filled with background noise (good thing for Dolby in my car!). But, with the WK-1630, I have always produced virtually noise-free recordings. And the bass doesn't overwhelm me when I play it back with a bass boost.
Speaking of bass, the new built-in speakers are also enhanced. While therir still 5-watts, the two new bass reflex speakers on each side really pump out the sound! Goto the analog drum kit (#196), and hit the bass drum on the C key. Try it with the volume slider at max. He he he!
My only complaint about it is the snare sounds in drum kit #1 (#192). They sound a little weak.