The Zeus is a mid-high-range paintball pistol, built well and cleverly designed but still with significant short-comings that have only been partially addressed.
First of all- it's very large. It's much larger than any conventional pistol would be because it's firing a .63 calibre projectile- the magazine (which mounts to the top of the gun, rather in the grip, to let gravity assist in feeding) makes up a lot of the bulk. It'll be a little hard to get a conventional holster to fit it, but many companies are starting to produce over-sized holsters for just this reason.
In any case, you'll be nothing but thrilled when you get it out of the box. It's made out of high-quality steel and milled aluminum, and it's got a lot of weight to throw around (which also makes it front-heavy). I've dropped mine twice from waist-height and it's still operating perfectly, sans a few scratches and dings. Magazine-feeding, normally quite cumbersome, is suprisingly smooth- you twist the angled end-cap on the mag to stop paintballs when you're loading it, and give it another twist to let them roll into the breech.
Once you gas it up, though, problems begin. Namely, the atrocious cup-seal and 12-gram tightener. 12-grams never sit properly in the cup-seal unless you're religiously careful- impossible during play- and the cap which forces it down onto the gas pin is just horrible. The G2 came with a small cap-mounted 'wrench' to help, but even with it it's difficult to do it fast enough to ensure you don't get a continuous leak. Assuming you don't lose all the gas in the gun 10 seconds in, it's horribly inefficient. This is assumed- unlike pumps, it needs to waste twice the gas to cycle the bolt- but having to change gas every magazine is a chore because of poor design.
It's still a blast to play with, though. It demands a different play-style that few enemy players know how to handle, and it requires you to make every shot count. The Zeus G2 is a fine choice for an enterprising player willing to use a bottom-line and external tank to avoid the head-ache of 12-grams- takes away from it as a pistol, but makes up for it in sheer fun.