Bear in mind for a moment that I'm not speaking from personal experience, just the information I've managed to gather from various boards.
The big deal about the epic pet is many different things.
First, when it came out, it was the Kunark era, and the level cap was 55, and Fluffy was god. Compared to any other pet available at the time, Fluffy outclassed them in every conceivable way.
Second, while Fluffy looks exactly like the standard Air pet, it combines the abilities of all the other pets - a self damage shield, some big nukes and (not sure on this) I think a Root proc. It hits harder and faster than the other pets, has more hitpoints, more armor class and all-around better stats.
Third, until Sony "fixed" the pulling technique referred to as "green pet pulling," Fluffy was still useful at level 70 for getting a single pull every time, and having the pet live long enough to get the mob to the group. The concept behind this trick was to summon a pet that would con "green" (gray, these days) to the mobs you were pulling. Since the pet was such a trivial kill for the mob, its buddies wouldn't assist, and you could trail Fluffy (and his mob) all the way back to the group safely with no adds. This was because of the tremendous amount of HP and mitigation for his apparent level.
Fourth is that, for purposes of soloing, Fluffy is better than any other pet you can summon before level 66. This may have changed a little bit with the availability of pet focus items, but last I checked it was true. Fluffy doesn't put out quite as much melee DPS as the 61 Air pet, but its self-cast damage shield and its mitigation make up the difference with room to spare. If you pit the 61 Air pet (unfocused and buffed only with your damage shield) against Fluffy (unfocused and buffless), Fluffy wins.
Fifth is that, even if you're completely out of mana, you can summon him from your stick. Sure it may not be much, but on a raid that your pet goes down, and the nasty AoEs the target is casting ate all your mana (like that nasty Girplan in MPG for the Cleric epic), it's better than walking in with your pitiful 28 skill in 1 hand blunt and beating on it.
If you're already over 65, Fluffy won't be all that useful, but I'd still summon the orb and keep it in your pocket just in case.
Edit: Spelling.
Edited, Jul 25th 2007 11:51am by nyteshayd
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Jiriki Sa`Onserei, 120/67k AA Wood Elf Ranger
Anadriel Starfire, 120/46k AA High Elf Mage