Yes, it is. My Druid Alt-Alt (as opposed to Main-Alt) will forever remain my GatherBot (Herb/Mine) because of Insta-Flight.
Although I do often wish those little birdy claws could hold a mining pick..

TBH I don't even gather that much as I hate farming (time is money and I generally can afford to pay someone else to do it for me) but it's nice to have a toon capable of doing so if I really need to.

now if only they'd let me transfer my rare recipes/mounts/pets to another char or let me class change my main, cause there's no way in hell I'll grind Molten Core each week again for years to get that Rejuv Potion recipe once more for completeness...

They can, however, fly towards a node but pop out of it before you actually get there. You will hurtle towards the node at the same speed as flight, but ready to mine as soon as you land. Mine, and then shift to flight form while jumping away for absolutely no downtime at all.

@eyhk also cyclone the competition on a pvp realm, mine, and then John Fing Madden them after cyclone drops.