I have the limited edition red version of the MPK 49 and I love it. The keys aren't weighted, but they have a great response and don't feel cheap or fragile like a lot of midi keyboards. The pads are also really responsive, and the built in sequencer and arpeggiator are great for quick inspiration.
This has been my main midi keyboard for the last four years, works great! It's a bit bulky though and I could probably do with something thinner with less features. I mainly play the keys so I think I've just discovered like 15% of what it's able to do. I've started to use the drum pads on it more as of late though, and that is a great add on. Has nice pitch and modulation wheels!
When using a DAW with mappable midi controls like Ableton Live like I use, having a MIDI controller with lots of knobs, sliders, buttons, pads and wheels is great. The pads are MPC/MPD style. The menus are a little wonky, and the keys are spongy for truly keyboardist type playing but for synthesis and MIDI controller stuff it works great. The drum pads feel pretty good, and can be upgraded with aftemarket pads that can give it a true MPC feel. In fact the MPC parts vendors allow you to customize every knob, slider and button. I might black mine out and get the thicker MPC style pads. There is an onboard arpeggiator that syncs to MIDI clock which is super useful. If they keys felt better, I'd make it my only keyboard, but my Korg M1 keybed feels infinitely better if I'm rocking a Rhodes or sampled piano patch. Also, controls can go out. I've only lost a couple of buttons over the years and they're probably repairable, but build quality could be better. It is still built better than most MIDI keyboards in the same price range. It is still my main MIDI keyboard input device to my DAW and via a MIDI to cv/gate converter, I use it to control my Eurorack modular too.