I got one too, it arrrived on Wednesday. So far so good! It is super lightweight and pretty accurate at 15 yards. I got one in .25 and it really shoots the H&N FFT's very well. My biggest gripe so far is the iron sights don't have adjustment for windage, so it shoots really nice groups, just 1½" to the left of the bullseye! By addding the stock and a 3-9X Bug Buster, I can easily zero it at 15 yards and it's still super lightweight!
According to Hatsan USA, the spare cylinders for the Je1 will be available early next year, and they will also offer the dual cylinder option separately, if you choose to convert the Jet 1 to a Jet 2 later on. Personally, I'd just get a spare single cylinder, they are small enough to slip in your back pocket and will double your shot count between refills. With the out the box tune, I'm getting two full magazine (12 shots) out of one 250 BAR fill.