You do have to be careful using Aether against characters with good meteor attacks, as Aether's movements can be predictable. I've seen plenty of Ike's get bashed by a good Ganondorf or Captain Falcon because they set Ike up for an Aether and were just where the sword needed to be to give Ike a good foot in the teeth.
QD I'd say is a very decent recovery option. Though the path can be linear, it can be held as long as necessary. This allows you to bait out a counter for it and then slip past when they don't expect it. Also, if you work on the timing so you'll touch the ground right as QD ends, you'll have (next to) no landing lag and can move into any offensive or defensive option. I've been able to QD into a Shield to catch a punish, and then OoS into some great attacks myself. Or slid past their attempts to gimp, and pivoted right into a f-tilt or f-smash to send them flying.
You have to be careful with going too high, as you'll enter the helpless state san. mentioned. You'll be right back into the air if your opponent is fast enough.