I use these for general nature viewing and the night sky. The optics are sharp, gather a lot of light, and the image stabilization is top-notch. On the downside, they are very heavy and you may well need to rest your elbows on a convenient (if available) surface to steady the image a little more and to avoid fatigue. Also, the eye relief is too long to enjoy the entire field of view with the cups in the standard position. But when folded down, they are hard and very uncomfortable on your eye socket. I took them to a pro optics shop and they could not solve the problem. I asked if they could slice a ring of rubber off the bottom of the cup and slide the rest down for proper relief, but they said that the cup has a lip that fits into a channel on the eyepiece barrel and it probably wouldn't be a good idea to alter it. If Canon will come up with a shorter replacement eye cup, that would be the ticket. Also, they really should supply, standard, objective lens covers. As it is, I use my Canon IS 10x30s much more often and would recommend that you be prepared to return the 15x50s for a refund if you're not happy. We're talking about a lot of money.
Pros: great optics, stabilization
Cons: weight, eye relief, no objective lens covers
This review was written in the old system and had content requirements that are different than reviews written today.