I have had a pair of Celestron Skymasters - I think they were 15x70's, and to be honest I would never buy another pair. They felt cheaply made, the optics weren't too bad - but a lot of curvature to the field from about halfway out to the edge.
Then to bang in the final nail, they broke - right at the pivot point near the focusing ring. It was only held together with the most minimal amount of metal, and it fatigued while I was adjusting them for my kids to watch a whale....
I now own a pair of
Pentax PCF WPII 20x60's, and the difference is incredible. Quality feel, much better eyecups - the twist-up type, much flatter field. Not to mention waterproof. If I had to buy more bino's I would definitely go Pentax. They are reasonably priced for the performance, but next time I would get maybe their 12x50's in the same range (here), as the 20x60's are a little hard to hand hold for astro use, but great for terrestrial use....
Hope that helps
Adam