I've been using Brightkite since it was in closed Beta.
At the time, it was exactly what I was looking for.
I traveled a lot for work, and I enjoyed being able to look at the little map of pushpins.
It was fun.
But it never really caught on.
I had some friends on there (and made some friends on there), but not a whole lot.
And then came Foursquare.
They took the same idea, but they turned it into a game.
While Foursquare isn't more popular with my friends, I get to play with complete strangers. People I don't know oust me as Mayor. I oust them.
I get to earn points.
As far as I can tell, they're worthless, but I earned them.
I can recommend things, like "try the ribs".
It makes using Brightkite kind of boring.
The one feature that Brightkite has over Foursquare is the ability to comment at a place after check-in.
If I show up at a restaurant, I don't know what I'm going to have or how long the wait is.
Brightkite lets me post countless times at a location.
Foursquare let's me comment with my check-in.
All other comments are in my stream, but not specifically at that place.
So what do I do? I bypass Foursquare for those follow up comments and send them directly through Twitter.
There's also no native notifications.
Brightkite let's me subscribe to my friends via e-mail and SMS. I also get notofied of comments.
Foursquare let's me get my friends check-ins via Direct Message in Twitter.
And as far as I can tell, there's no way to comment on a post.
So Brightkite has the features, but Foursquare has the sparkles.
If Brightkite wants to compete in this expanding market, it's going to need to get some bling.
(Gowalla just frustrates me.)