PokeVision going down has killed a lot of the interest for me too.
I spent pretty much the entire day yesterday, out and about looking for Pokemon that I didn't have. I ran out of the flat twice (once at 1:30am!) because PokeVision showed a Magmar had spawned nearby.
On Friday, a big group of people from my office and surrounding offices flocked to entrance of our business park because PokeVision showed a Snorlax appeared.
Without it, I'm not quite as keen on the aimless wandering around. I've got a couple of places to hit up today, based on what I saw on PokeVision before it went down but, after today, the game will be a background thing for me - I'll turn it on if I happen to be somewhere rather than it specifically getting me out of the house to places I'd never normally go.