It seems like an instance of "Yet Another Photosharing app", which is getting tiresome. Sometimes reading mobile development news makes it seem like photo/status sharing, and todo lists are the only things people do on mobile phones.
2) Friend limit. This changes the game quite a bit. You have to be conscious about choosing whom to add, which will most likely lead to adding people you only wish to share with.
3) Taking this into account, you will be more inclined to share things with people that would care to interact with it. On Facebook it would be stupid to say you are awake, or asleep, but on Path it makes more sense, because you are sharing with the people you care to share with.
P.S. Anyone have an HTC Wildfire? I've tried installing it, but it doesn't work although the minimum is specified as 2.1 on the market?
And that's why they're not going anywhere.