Ok for the price if you get one that works... - Barska 4x20 Electro Sight Rifle Scope for M-16 Carry Handle Mount

You get what you pay for, and you pay for what you get. This is a cheap scope, so manage your expectations. I wouldn't trust my life to this scope, but it's fine for plinking, which is what I expect at this price point.
The first one I received would not adjust elevation or windage at all. Opticsplanet gave me a full refund, so I decided to roll the dice a second time. This one adjusts, and I was able to zero it quickly and hit a steel plate at 100 yards. I'll have to spend some more time to see how well it holds zero over time and how the range adjustment performs. I'm giving it 3 stars since this one seems to work, but I'd only recommend buying it from a company like Opticsplianet that will take care of you if you get a dud.