I did a pretty exhaustive search for a full-featured, low-priced controller. This is where I ended up and I am happy with it. These things are obviously built to a certain price point, and with that in mind Nektar have done an excellent job.
I'll start with the negatives...there really aren't that many of them, and they are nitpicky. It would have been nice to have aftertouch and a MIDI out, but those are features that few other controllers in this price range have. They keybed is nice, but not great...it's a little "clicky" and doesn't offer a whole lot of springy resistance. That can make rapidly triggering notes a bit difficult. But otherwise it feels nice, and I preferred it to most other controllers in this price range. Also, something about the look of the new + version bothers me a little...the combination of hard plastics, right angles, and muted colors reminds me of cheap hybrid synths from the '80s. But when you turn it on, the glow of the pads makes things much more exciting...
Speaking of the pads, they are excellent! The best I have used so far. The knobs turn very very smoothly and feel nice, as do the pitch and mod wheels. The sliders and other buttons feel good as well. So, the overall build quality seems great.
Where this thing shines is in "digital integration." Using the Impact LX49+ with software that shows realtime response to knob and slider movement is a real treat...everything is very smooth and precise and looks great. What you see on the screen is exactly what you're doing on the keyboard. For the most part, it's also plug-and-play, and it just works. Nektar have done all of the hard work of mapping things for the most common DAWs, which is a blessing. I will say that I expected configuring the Impact to work with different DAWs to be a little simpler. You have to create a user account and download files from Nektar's website and then run an installer. My first attempt at GarageBand integration didn't work. But I didn't try again, I just moved on with my life and I am confident I will be able to get this controller working with whatever software I need. Things are also reasonably easy to change on the keyboard itself. The display is pretty limited and the system for data entry is a little archaic, but it works well.
So, minus 1 star for the feel of the keyboard and no aftertouch, but high marks in all other categories. If you're looking for a budget-priced controller keyboard, this is an excellent choice. The more I use it, the more I love mine!
Quick update: got the Nektar working with GarageBand. Piece of cake! I realized that I had accidentally registered it as an LX49, not an LX49+ (which was buried further down the list). Once I took care of that and downloaded the right files, it was quick and easy and flawless. Really enjoying using my Nektar Impact LX49+!