It has it's pluses and minuses.
Very easy to use from the phone, and the text is straight away a good size to read, so no messing with trying to get it big enough to read, but small enough to fit on the screen.
You can use it for many forums, which makes keeping an eye on several very helpful, we use it on our 4x4Responce forum, so it is easy to check in regularly to see what is going on, and saves them money, as they only have to use the SMS system in emergencies, rather than call-outs that have a good lead time.
Nice and easy to respond to a post, and post pictures as the others have said.
Bad sides.
In order to let you know if you have any PM's, it checks the forums regularly, and on this forum, every time it checks the messages, it marks all the threads as read, so it is very easy to miss new posts, or as I have found, answers to my own posts, unless you make a point of remembering the last time you checked, and going back further than the few it is showing as new. The problem then is, it goes to the first post, rather than the last read one, which on long threads can be a pain.
You can't see any of the info or footer on a person who has posted in a thread, so if they leave out the model of their car, or their location from the actual post, there is no way to know that by looking at those bits.
You don't seem to be able to get to the Links, and downloads section.
I personally still prefer using the laptop, which makes looking at the pictures a lot easier, and finding your way around is far better, but it is useful to keep an eye on things when not at home.