I tried a couple, and actually found that for MY eyes, they worked very well at the longer magnifications ie 14x.
I tried some other "non-brand name scopes" as well around that time, and had to send a couple of them back, as they went blurry when zoomed out to max range. I shouldn't say "they" went blurry - everyone's eyes are different, and those 2 scopes just didn't work for me.
But the Nikons did, and I still have one of the Monarch UCC models. One small complaint... it is a BDC model, and the bullet drop circles tend to get in the way of a good sight picture.