Bought one of these for a laugh, arrived yesterday, nylon .50 cal balls arrived today, and me and the boss spent an hour this morning smashing redbull cans to bits with it.
Great fun. Loud! Not really suitable for suburban garden use I would say, though with paint or chalk balls (and eye protection) it could be quite safe.
On the continent these - or their more powerful 'HDR 50' cousins - are sold as 'non-lethal' 'home defense' weapons, an interesting concept but not something to be elaborated on here. Frankly I was a bit sceptical, but I certainly wouldn't want to be hit with it.
Anyway what you get is a great big black ugger of a revolver, picatinny rails top and bottom, supplied with four detachable cylinders/magazines. Stock sights are basic and fixed but it does shoot near enough to POA at 6 metres.
CO2 feeds into the grip, nozzle down, and the caplet is pierced by striking the nut/piercer with the palm of the hand - in this way in can be stored with an unpierced caplet without wearing seals or leaking. Once gassed a little button pops out of where the hammer would be if it had one, to let you know it has pressure. I quite like this feature and think it should be on more CO2 guns. After gassing the loading sequence is; push spring loaded cylinder axle forward and up so that it locks, load cylinder in from the side, snap back cylinder axle.
.50 cal nylon balls are a nice snug fit in the cylinders, and if fired against something reasonably soft seem to be quite reuseable. Rubber balls are available but I should imagine they will be ricocheting all over the place.
Construction wise it is mazak or similar alloy shrouded in plastic. We expected this. Quality of moulding is decent and it seems reasonably robust but we know this isn't heirloom quality.
Safety is in the trigger blade a la Glock, and the double-action only trigger itself is quite a long stiff pull, but predictable, indexing the cylinder on the initial stroke.
Did I mention it was loud? It's loud. After some practice reasonable accuracy could be attained with rapid fire. Power drops off quite rapidly when firing quickly, but when pacing out shots there seem to be about 24 or so good shots out of a caplet.

Should you buy one? Perhaps not for the use intended for it on the continent. But if you have an isolated area to shoot in, have slightly more money than sense and like loud noises then you could have great fun whacking about reactionary targets at speed.
If you are a paintballer and if this would be allowed in the field (I have no idea about paintball site power limits etc.) then I think this would make a nifty little sidearm at a reasonable cost compared to many other paintball pistols. The price for these did vary considerably though, so shop around.

That's about it for now, questions welcome.