In short, I'm really impressed. It's all-metal (die-cast, but metal nonetheless), the magazine loads through the bottom of the grip, double action or single feel close to the original, working slide, accurate, and somewhat powerful for a BB pistol. A great training aid for Mak owners. The only other CO2 pistol that I can compare it with is my GAMO PT-80 and the Mak just comes across as being more realistic and of higher quality. My only complaint are the cheesy plastic grips, but the original Mak has cheesy plastic grips as well. Maybe Pearce grips will fit? (edit, I checked, not without extensive mods).
It should be noted that UMAREX is a German company and known for high-quality air-guns.
The attached picture shows a 2 inch, 5 shot group from 30' (exit side shown). As you can see, three of the shots are within a 1/2 inch with two flyers.
The best part is? I shot this group in my basement

Now if UMAREX would just make a CZ-82 and a P-64 version......