I've owned one a few months. At the time they offered a third Laser Etched option. If you look around on the site there still are some pictures.

I guess the Continuum history is the first surface was unmarked and people did have a problems finding pitches. The laser etched surface was the second. It's definitely subtle in low lighting conditions but in decent light it's fine. The third and newest surface has the dyed sections for the black "keys". You can supposedly feel the dark areas but I've never actually tried one. The laser etched surface can be felt but it's really subtle. I've not found the touch of the etched lines a playing aid but with concentration it might be possible.

Dr. Haken implied that it might be less durable but he also mentioned Jordan Rudess was the only user to ever need a replaced surface. My guess is he stopped offering the laser etched surface because of decreased orders but I don't know. He might even still offer it on request but that's just guessing, anyway last fall I knew I wanted some markings and definitely liked the laser etched look in photos. So my conclusion is I'm happy with the laser etched surface but now I think I might like the dyed surface to make the half steps even more obvious.

As for playing it, it is quite different from a keyboard, not so much in the fingering as the pitch spacing is the same but the whole concept of pressure entirely controlling the amplitude. It doesn't seem like a huge difference but I think it is after I tried.

There are a lot of inspiring configuration options so you can do things like send gates even velocity with some considerations of their behavior. I think the initial rounding feature is incredibly useful as well as a feature to subtly quantitize a pitch after a a user set amount of milliseconds. So when enabled the initial pitch from touching the surface will be "on the money" through quantitizing, then any sliding pitch change goes live, then on stopping the Continuum has an option to continue and slide subtly to a quantitized value.... and the quantitized values don't have to be even tempered, they are user programmable with the online web app that generates sysex for it.

I'm excited about the onboard digital synth too. It's not very publicized (or programmable yet) as it's still in development, but it's creating polyphonic sound onboard and one can certainly send it through your modular if you want to.

As for the CV interface, the Haken one has a lot more resolution because it's not actually dealing with MIDI (despite the use of a high spec MIDI cable for communications). As far as I know there is a decent discount (I forget the exact amount -- around $250 $300) for buying the CV unit with the Continuum at the same time so if you thought as I did after the Continuum purchase you might want to put off buying the CV interface for later then ironically it might cost you more in the end. Also my thinking is that if you are going to spend that much money on the Continuum with a CV instrument being what you plan to use and master it then you probably don't want to add a big compromise. Maybe if you only dabble with CV and mostly use software instruments or something then I could see why one might want to postpone the CV interface for later.