Got my hands on a Movi a bit over a week ago, spend some time playing around with it.
My verdict:
Interesting. I wouldn't call it revolutionary, but it is an interesting way to get some shots. I wouldn't say it's any better than other, more conventional rigs, but it can be much easier to get some cool shots.
Few things I found:
You need someone who has some experience operating it to do it. Newbies can technically operate it, but I noticed that the shots from newbies versus those who had been using it for a while (on all three aspects - rig operator, remote head operator and focus puller) is vastly different. Newbie shots tended to be quite jerky, despite the massive stabilisation. You also need your operators to be completely in sync, and you need to have planned out exactly what the shot is of. You need to know where to hold the rig so that you dont get yourself in shot, you need to figure out where you'll need to be at certain points.
For professionals and/or people who work well together - established DP/Op/AC teams that have worked together for a while will likely find this a lot easier than those who are brand new to it, or trying to assemble a team for it.
It also takes a long time to stabilise. I guess it's similar to a Steadicam in that respect, but it's more difficult to stabilise as you have more axes. Of course, the more you do it, the better at it you get, but you're not going to be able to pick this up from a rental house and be shooting the next day, unless you have someone who's done it stabilise it at the rental house, or you have someone on set who can do it. After it's stabilised, you can pull off steady shots with relative ease.
It's also pretty heavy. The one I was using was rigged with a 1Dc and IIRC a Canon Cine Prime. It's not the weight of a full steadicam rig with an ENG or Alexa on it, but it's pretty heavy and unfortunately it's all on your arms. As soon as I picked it up, it felt heavy - again not majorly so, but heavy enough that I wouldn't want to attempt to op multiple takes of every shot throughout the day on it.
Overall, I think it's a great tool that will be useful for a number of shots, particularly those created especially for it. I don't think it's going to be replacing the need for a steadicam, jib or dolly anytime soon.