When I got mine, you couldn't find anything positive anywhere about the Colt except that it looked good. The controls on the 15-22 replicate the controls of a real AR more completely. The 15-22 is missing a functional forward-assist. The bolt release on the Colt is for looks only and serves no functional purpose. The 15-22 accepts many AR parts. It uses a mil-spec receiver extension, allowing the use of any mil-spec stock. You can use AR grips and fire control parts (small-pin only 0.154").
If you decide that you like the Colt, you can also look at the H&K versions. They are also made by Umarex.