My feelings about it are summed up by Ryan Mickle in his post When free makes your product suck:
I realized that Twitter is turning the corner from a beloved, worry-about-making-money-later company into a just-barely-tolerable advertising machine.
So I’m looking for a way out. I don’t care that much about posting new tweets (that’s just a bad habit), but keeping up with some interesting people (oh, and the team at work) is something I’d like to do.
A little while ago I set up a local version of Tweet Nest, which is a fairly simple backup of the content you post to your twitter account. It was easy to install and works fine for just keeping a backup of what I’m saying.
ThinkUp is a more advanced version of the same idea; it keeps what I’m saying but, according to the site and this brief review, everything else as well. A one-stop twitter-backup solution including threaded replies, graphs of followers and a summary of all the links that people have tweeted. I’m fairly tempted to install this and start using it as my primary interface to a read-only twitter.
Will twitter miss me? Probably not. Will I miss out on contributing to conversations? Probably. Am I OK with that? Absolutely.