Does anyone have experience with the ATN Ultra Sight Digital? I'm very interested in one for an AR-15. I know that there is ALOT of choices out there, but can't aford a RED Dot. Thanks in advance.

I acquired on on a T&E.

For serious use... NO.  The allen screw sight adjustments locked in place by friction from a third allen screw.  Battery life is only about 100 hours.  Field of view is narrow. The sight must be removed from the mounting base to change the battery.

I do like the selectable reticle.  For fun I'd put one on a pistol.  I'd never use one on an AR.

Save your money and get something better!

I'm a huge fan.  I have used them only on pistol caliber AR's and I wouldn't use them on a primary firearm due to the exposed 'windshield' as opposed to the Reflox or Mepro's protected glass.....

the reticles are IMO the best out there.  The T with no dot is my favorite, the chevron next.  I don't like having large reticles ON my target and in that role, these rule.  Same with Kobra's, Tripowers, etc.  

BUT the new aimpoint has a reticle small and sharp enough that I'm not a convert with many M3's!

Anyhow, for the money, and for range and even class use, I like the ATN.  The battery does have an auto off at what 10 hours? and it will not cowitness on a flattop, but here's a little trick, it WILL cowitness on a surefire handguard.  and ONLY a SF handguard.  IT gives you a perfect bottom third cowitness on a rock solid mount.

The one I am T&Eing will stay on until the battery goes dead!