Well, you should definitely watch it again. It's a very progressive, experimental story. My favourite of Season 25 is still Remembrance of the Daleks (Masterpiece!) but Greatest Show is a close second. The only weak link is Silver Nemesis. It's still better than any of the New Who Cybermen episodes (Unless we count Pandorica Opens!), but it feels too much like a rehash of Remembrance and the Cybermen aren't handled well in it. They were far more threatening in Earthshock and Attack of the Cybermen.