Have handled, shot and saw one being disassembled.
In short; don't even go there.
Disassembly and cleaning is horrible. Here is the official instruction video.
Colt .22 M4 and M16 Rimfire Rifles - Field Stripping, Cleaning, & Adjustment - YouTube
You need tools to fieldstrip.
You cannot take out the bolt carrier. (on a .22 semi-auto?)
I went over to the dark side and got me a M&P 15-22. Yep the Smith and Wesson. Sorry folks.
One drawback of the M & P 15-22, it's light. For some maybe to light.
But that's the only drawback I can truly give. It works. Period. Pull the trigger and it will go bang. It swallows almost everything I put in the mags. Including Winchester Wildcat ( the manufacturer states not to use that). I haven't shot any Remingtons yet, but am tempted to try. And when one is only tempted to do something stupid like putting Remington-ammo in a .22 semiauto, then that makes one wonder. The mags are not as chunky as the are with the Umarex.
No tools needed for fieldstripping. No weird parts coming lose that don't have any function.
The bolt carrier comes out faster then one can poor a beer.
Don't like the trigger? Those S & W-guys did something horrible...
You can drop in any milspectriggergroup you can find! Yep. Just get your milspectrigger and drop it in like you would do on a true AR-15 and rock and roll, baby. Same goes for grips, stocks and anything els externally. Get your own goodies.
On the Umarex that ain't never gonna happen.
Here's a fun vid on it. It also shows how easy it field strips.
(field strip at 32:00. note the tool to get the pin out. I do not need that tool and I do not have kryptonite in my fingers)
Don't go for the Umarex. Get the Smith and Wesson M & P 15-22. It's a better gun in many ways.