tldr; >600 miles, no unexpected nose dives. If you're dog is cool with it, get it.
I clocked ~600 miles before winter set in and had exactly 1 nosedive. It was entirely my fault. Tried to accelerate reallly hard through a crosswalk going up hill. Float plates saved my hide since it let the board skid for a bit rather than just biting concrete. Ran it out, lived to ride another day.
Best pieces of advice I have:
Let the board do the acceleration for you as much as possible.
It's a pretty mighty board, but doesn't like jumping from 5 to 15 at an instant. Trying to do that just means you're gonna jam down on the front increasing your chance of eating gravel.
If you're going to ride hard, ride engaged.
There's absolutely nothing wrong with cruising up West End at 2am with some fries in your hands and a good feeling in your head, but if you're going to bomb down 7th, you don't get to ease up.
Fenders and Float Plates
You'll want these: http://thefloat.life/
Check with you dog
Not all pups like the boards and some are down right mean about it if they're not out right scared. Some people are down for dogs on leashes while they ride bikes and boards...Not sure I'm one of them. I'd hate for my boy to suddenly careen into me :-/
Learn to ride good
A list I made of stuff to work on: http://community.onewheel.com/topic/7290/nyc-riders-help-out-a-total-newbie/4
Practice practice practice and it'll become 2nd nature. NYC has a pretty decent community and everyone's been friendly that I've met. They're usually down to ride with new people. Get on some of the FB groups, etc...I'm in the UWS and it's a pretty decent area to tool around in.