I first looked through a spotting scope on the Isle of Mull in Scotland. A chap had set his scope up looking at a family of otters and let us have a look. The view was really amazing, and although I never thought to see what make his scope was I had to have one. I read as many reviews as I could in my price range when I got home, and decided on the Celestron Ultima 80. I have not been dissapointed. I think that for the money this scope is very good. I have been birdwatching at Rutland water with a mate who has a Kowa scope. This is a quality (read expensive) scope, but the Celestron very nearly matches it, and actually has a more powerfull zoom. I must admit that the brightness of the image decreases at the max 60x, but this is to be expected. I usually use the scope between 20 and 40x mag. where the brightness and clarity is very good. I have used it to look at the moon and the planets, and with a sturdy tripod the results are very impressive. If like me you can't justify spending serious money on a scope, I can recommend the Ultima 80.
UPDATE AFTER 18 MONTH USE.
I continue to be impressed by my scope, but I have now looked through a lot of very good scopes (Swarovski, Leica etc.) and I decided to improve my scope with a better eyepiece. After a good deal of Googling I decided that the Baader Hyperion zoom was what I needed. This fits straight on to Celestron spotting scopes, the only downside being the price (APPROX. £180 NEW). After a patient wait I managed to pick up a second hand one off Ebay. I fitted it and went to my local gravel pit to try it out. WOW!!! Absolutely awesome, the difference is outstanding. The field of view is much wider and the image crystal clear even when zoomed in. I recommend this upgrade to anyone with a Celestron scope.