Does it really matter that it isn't tied to Google's ad ecosystem if it has its own revenue stream (paid plans for increased storage)? I know everyone's been a bit shaken up with google's flurry of closures, but this isn't like reader, it's actually being monetized. Not to mention that Google recently consolidated Gmail and Picasa/G+ photo storage into Drive accounts -- this hints that google's long-term plan might be to treat Drive like a sort of unified storage system. This makes sense given google's recent push to unify everything, and should ensure it some stability. If anything, it's more likely that they'll kill off Chrome OS/Chromebooks (which heavily rely on Drive) before they kill off Drive[1], so I feel relatively safe with it. I would go so far as to say that Dropbox feels just as safe because Google isn't exactly a competitor that should be underestimated (despite their many flops).

Either way, I use Docs way too much, to the point where I always have a tab with it open, and Drive really ties everything in quite smoothly for me. I also like the Drive app a bit more than the Dropbox app on my android phone, so not really a strong incentive for me to switch back. I actually never made much of a conscious decision to switch to Drive in the first place, it just kind of happened automatically due to convenience, and now I use it almost exclusively.

The only thing that does bug me is the data-loss. I haven't had it happen in Drive proper, but it happening in the short time I've used Keep certainly lends credibility to it being a wider-spread problem. We'll see...

[1] Not that I feel ChromeOS is 'safe' from the killswitch, but it's still a bit too early to tell what their plan is for that exactly