I bought this to see if it is worth it to pay 300 bucks for a red dot... I prefer iron sights any day. I never used it on the range, it feels very unnatural to look through the sight looking for the dot. It was worth $25 to test it.

UPDATE:
I took the sight to the range and decided to try it, as my safety glasses would fog up and make accurate sight alignment challenging.
The first shot was high, so i finished the mag which was also high. After adjusting the sight with a torx screw driver, the grouping was a tad bit high, so I adjusted again. With the third mag, I was putting one round after another through the same hole!, about a quarter size when finished. I was truly amazed that the sight was that good! Now YMMV, as I only shot about 50 rounds through my 1911 S&W rail gun using a amazon purchased picatinney clamp that attached to the non-moving frame. With these results, I feel good about shopping for optics ready firearms. In closing, I'm not sure if it would help in a gun fight, but it definitely will improve your range performance.

Update #2
When I mounted it to the moving slide of a glockusing a picatinny tail the dot moved way to the left and high and could not be adjusted.
I took a close look and discovereda major design flaw, the viewing window is glued in place from the front, and only takes a few shots to work is loose from the housing.
It will be repaired and used for stationary use only at the range, and I must give it only one star.

So far, so good. For the price, this is doing what I expected it to. I am using it on a rifle that has no iron sights. I do not like scopes, so this is as close as I'm going to get to open sights without having them installed by a gunsmith. It's clear and accurate enough. This is not a $400 or even a $100 red dot sight, so don't expect it to be as good as them. A couple things to keep in mind versus tube style red dot sights: these are not as sturdy as tube style and debris can get into where the laser comes out. Tube styles don't have this problem. But, if you are wanting an open style red dot for a low price that works well enough, this is pretty good. I am satisfied with buying it. I don't know that I would want to use it one something with high recoil, like a .30-06 or a 12 gauge shotgun, simply because I don't know how well a $30 red dot site is going to hold up under those high recoil situations. I'm using it on a bolt action .223, and it's working thus far. REMEMBER TO BACK THE LOCKING SCREW OFF BEFORE ADJUSTMENT OF WINDAGE OR HEIGHT! The locking screw is on the right side, inside a little hole, and uses the smaller of the two Allen wrenches to adjust. Back it off one turn, then after adjusting your sight, tighten it back into place. Go to AIM Sport's website for instructions on this.

Now own two of these rascals. Comes with a spare battery and two ellen key wrenches. The price here is better than anywhere else... don't get ripped off thinking "Oh that one is $70 must be nicer" not true no it isn't. These are as good as any red dot holo under $100!! Granted, there are better but not until you spend some real money.

Works on the AR, the 10/22 even shotguns according to some of the reviews listed here. I can only vouch for a AR in 5.56. It stays where you adjust it, fun to use, not a single complaint.

Don't leave it on and kill the battery!!!! With proper use the 2 batteries should last you at least a year or more. My original still works fine that I bought almost 3 years ago.

UPDATE A MONTH OUT: This optic isn't really working out for my 10/22 take down. It could be the rail I have, but it just would not work. Nothing wrong with the device at all, but have not sorted out the issue on the 10/22. Works great on my AR no problem.

This sight blew me away when I received it. First off, the packaging was spectacular. Everything was tightly packed so as to minimize any shifting, jostling, or damage while shipping.
Then, when I actually got around to testing the sight, it was amazing. I tested it around noon and aimed it towards the sunlight while standing outside and all of the reticles showed up clearly. Some had to be put onto higher brightness than others but it was still incredible!
Also, the compact size and ease of access was perfect. It takes no effort whatsoever to switch between any of the reticles. Changing the brightness is almost as simple and equally as accurate.
The brightness settings are insanely well done. With seven levels of brightness, you can operate this RDS anywhere from broad daylight in summer to the deepest recesses of night.
In all, well worth the money, more than any other optics I've owned by far!

The sight was made well and the materials are of good quality but I could not sight this in for the life of me. I maxed the elevation of the dot and it was still a good 6 inches off when I would fire at the bulls eye. One of my buddies got this same one and had the same exact problem.

I would recommend skipping this sight and going for the one with the red and green color, took me less then 5 minutes to sight in with a bore sight and it has worked great ever since.