I've owned my 18x50 binocs for two years now, and have used them mainly for astronomy. Perhaps my expectations were too high, but...
(1) I found the image to be less stable than expected. It's certainly better than with no IS system at all, but not as solid as you'd get from using a good tripod. Of course, using a tripod near the zenith is a problem, but there are solutions for that, such as the Sky Window system (the binocs look downward, at a mirror). After an hour's observing, you'll definitely notice how heavy these binocs are.
(2) I found a large amount of residual color on bright objects...red on one side, blue on the other. I attribute this to the prisms used in the IS system.
(3) The maximum interocular distance is just barely wide enough for my eyes. The diopter adjustment has considerable stick and slip. I'd rather wear my glasses than mess with the diopter, but the eye relief isn't sufficient.
(4) The binocs come without lens OG lens caps, which is strange, considering how expensive they are.
I suggest you NOT buy this binocs online. Go to a store that will let you take them outside. Examine a star-like object, such as sun glint off a power line insulator. Check out the IS, the residual color, and the weight. See if the store will let you have them "on approval," and try them out at night.
And don't forget, you can buy a pretty good apochromatic telescope for $2000.
Roger Rensvold
Hong Kong