I've been using MoblogUK for close to two months. My mob, "Shiny, Pointy & Tall," is devoted entirely to pictures of tourists taking pictures of the Chrysler Building and has gotten a lot of comments and response. You can view it here.
http://www.moblg.net/blogs.php?show=730
The service is ad-free, but you get more features the more you donate. I think I kick in $5 a month and get everything there is. The system is not particularly flexible, however. There's a handful of templates, but other style sheets have to be uploaded by hand by the admin. I haven't bothered. If you want something more flexible, you should probably just build your own with Movable Type. If, like me, you just want a moblog to link to from your regular blog, this is a good way to go. It's a real mom and pop-type operation, the service is personal and all the users are very friendly.
Also note, Smartphone users, that all the pictures on my moblog were taken with the ViewTake camera attachment for the MPx200, used with a locked AT&T issued phone. Not too bad, eh?
jim
long-time lurker, first-time poster