Personally, I think Twitter is struggling because they're married to the greatest short coming of the product: the 120 character statically allocated array. Sure they've tried to shoehorn other things into it (photos, replies, tags), but always at the expense of these precious characters -- a product decision that came from aping SMS. The updates are often frustratingly limiting. As long as you artificially limit yourself, you're stuck and can't innovate.

I use Twitter, but I don't know what I exactly get out of it. I guess I use it out of habit more than anything.