For a while I thought i was on the S&W 15-22 infatuation board. I decided to spend some money and save some at the same time. The folks I talked to around here all seemed to favor the S&W. But when I looked at them and felt how "plastic" they were, I decided to look at the umarex. Solidly built,not "all plastic". Since shooting it for about 2 weeks now and about 1000 rounds,I have yet to have a FTF or aFTE. I've used several different rounds, and have never adjusted the speed as they call it. Also, did I mention it was $100 less than the Smith. Needless to say I'm pretty happy with mine.
Some people, like myself, wanted a gun that functioned similar to a real AR, not just look like one on the outside so that I could mimic my 6920 as close a possible for training/skills carry over.
If the Umarex suits your purposes and you like it, it was a good investment no matter if you saved $100 or spent $100 more.
Personally, I don't want a gun that has functionally irrevelant parts on it just for looks.