talking of the moonlander here, they float if you drop them in bodies of water. they are heavy, yet fun, you will either bounce around, or dent the rim, if you'll try to tackle rough patches of trail at speed. the steering precision isn't superb but sufficient. imho unsurpassed on sand and snow, haven't been in really mucky conditions with it yet.
I have a buddy absolutely shredding every type of trail possible on one. I gave it an honest shot on a DH run and it felt like my forearms were going to explode, and the cornering was scary, but it does monster truck sections and climb amazingly well. You can stand up mash pedal steep ass sections where the regular biek would break loose constantly.
My friend seems to think its the best thing going, and he backs it up by hanging with everyone on 7" travel freeride bikes, which I think is pretty impressive...
I think if you have an open mind and want something different, they can be a blast- I mean- it is a bike after all!