I just got an old maschine mkI, and I absolutely love it. I have been producing pretty much exclusively on the elektron machinedrum in the past (and ableton chopchopping when arranging), and the maschine is like a machinedrum which can control vsts and has an insane library of samples and drumsynths and effects.
One thing that is just a tiny bit annoying is making polyrhythmic patterns, as a scene (a selection of pattern for each group) is always the length of the longest pattern, which means that for a single 3 against 4 rhythm you need a 12 bar empty pattern in the mix. I use reaktor blocks however for a lot of the polyrhythmic things, so it's not too much of an issue. I barely have to look at the screen with the mkI, and had a studio lent to me for 2 weeks by a friend, where you really don't have to look at the computer at all. However whenever I want I can just use the software on the computer without the controller (on the road, in public transport), work on that, make some sounds. The integration with all the NI instruments is pretty great too, the sound browsing / tagging can get a bit confusing at times, but then, I spent years on the machinedrum
You have a step sequencer, but you can easily play pads live or switch to keyboard mode (playing the pads like a keyboard). The keyboard mode has a scale / chords mode which is great and enjoyable. The step sequencer has paramlocking like the machinedrum, and you can edit sequences entirely on the maschine (nudge / transpose / copy / paste notes), although that's the point where I often go back to the mouse and fine tune on the computer screen. You can record automation very easily (it's actually hard to draw in automation with the mouse).
Another thing I really enjoy is the slicing / sampling capabilities, which make it trivial to import / record whatever weird loop you have going, chop it to pieces, make a new kit from it, save it to your library for future enjoyment / reuse. It feels almost too easy in a way, as every pattern sits incredibly tight in the mix, and if it doesn't you can easily eq / transient master / compress every sound / every track, resample, reslice, replace.
What it is not is a DAW for sequencing your entire tracks, you can lay down stuff with scenes and patterns but since 80% of my work when doing a track is taking a finished pattern and then scultping the choreography / swells / tension / adding chopchopped samples on top, that's where I revert to ableton. Since you can load it as a vst (multiple times! you can just select which instance you want on the hardware on the fly), it's easy to dump the output to wav / draw in automation in ableton for longer sequences.
Another thing I was missing is that even though it has macro controls (per sound / per group), each of those macro controls can only control 100% of one subordinate control, not like ableton live racks where you can finetune the mapping of a single knob to create complex sound transitions. But then again, if you compare it to the machinedrum :} :}
One thing I haven't tried yet is playing live with it. I'm very used to the machinedrum for playing live, and I use the "shift-holding" track mutes a lot (to queue up whatever i want to mute/unmute on the next breakdown), which doesn't seem to exist on the maschine. You can program it in using scenes, but that requires you to think ahead of what permutations you want. I might give it a chance with a separate midi controller.
It's only been 2 weeks since I got back into making music, but here is the result of 1 hour jam with maschine: http://bl0rg.net/~manuel/maschine-test.mp3