If I had a WoW character with RP reasons to ride a celestial pegasus...I'm not sure. I'd give it serious consideration.
However, as I did not have such a character, I'd have no reason to get this mount. I use the flying mounts that are one of three things:
-easy to get
-aesthetically pleasing
-thematically appropriate for the character
Usually in that order, with the last two sometimes switching places. Thus, my time/plane-traveling rogue rides a bronze drake, my blind magic-steeped warlock rides her carpet, my laid-back death knight...actually I don't remember what she was riding. Hm. Probably also the bronze drake just 'cause it was easy to get, but I don't recall. Haven't played WoW since August '09 (8 months sober, woohoo!), it's a long time to remember what mount of convenience I was using on the DK since she didn't really have a thematically appropriate ride available.
...in the air, at least. On the ground, Shjade rode a hawg. In appropriate biker gal attire. ;p
So yeah. I'd skip this one. No character that would use it theme-wise and it doesn't suit my taste - too shiny. I'm sure it'd look cool and all, but I'd get tired of it long before it would pay off the $25 spent to get it.