A Great Device, But Not 5 Stars
This review is based on my initial impression, so please take that into account. In my time recording in my own studio, I have used now eight different keyboard/controllers, most from different manufacturers.
First, given the price of the 61SL MK II, I think Novation should have included a power supply (minus a quarter of star for that).
Second, there was no owner's manual included, either in the box or on the disc (and there's plenty of room on the disc) or not even at least a direct link to an online manual; I personally, actually LIKE reading owner manuals before I delve into a new piece of hardware (minus a quarter of a star for that).
Third, a couple of design flaws: The control surface should have been tilted toward the user. As it is, it's hard to read the LCD without leaning over the keyboard and it's also a bit inefficient reading the positions of the LED's on the continuous encoders. The other flaw is the location of the faders. On the 61-key model at least, they would have been better off located to the right of the buttons currently below them; that way they could have had a longer throw. Quite a bit of wasted space there (minus a full star for the two design flaws).
All that said, I'm not significantly dissatisfied with the 61SL MK II. In fact I think the keyboard 'action' is about the best of any I've had and once I devoted about an hour or so of slightly more than mild frustration, I have most of the controls set up to work the way I want them to in Pro Tools 11.02. Automap is powerful stuff, but if you're new to its functionality, a bit of patience will pay big dividends. I also much prefer the joystick-style controller for Pitch Bend and Modulation rather than wheels, which was in fact one of the important deciding factors for me. Overall, the device lacks some intuitiveness but makes up for that in power, flexibility playability and build quality.
The one real problem I do have is that, if the SL MKII is connected and turned on, when I launch Pro Tools, it consistently fails to initialize my MOTU Audio Express audio interface. None of the three other controllers I've used with Pro Tools have caused this problem. I managed to figure out that I have to turn the SL MKII off, launch Pro Tools, then turn it back on as soon as the audio interface has initialized; everything then works without issue. I'm still troubleshooting that, and I'll be generous and not knock off any stars for it just yet, unless I discover that there is no solution.
Still, I would not hesitate to recommend this device, just make sure you're aware of it's drawbacks and be honest about whether, given the price you'll pay, you're okay with living with those drawbacks.