I've been using Twitter for a little over a week - and as you can no doubt guess from the title of this post, I've had mixed experiences.
I've managed to pick up a handful of useful links to software development resources. Plus, I like how many of the mainstream blogger's "Tweet" when they make a blog post - it's kind of like real-time RSS.
However, I have noticed a less than desirable signal-to-noise ratio. Whereas most of the blogger I follow publish software development related content, following those same people on Twitter has thus far yielded dissimilar content, and out of context chatter. For example, if you are following one person, and they "@reply" to another person you are NOT following, you only hear one side of the conversation - much like trying to overhear and understand a phone conversation that you can only hear one side of. I've also noticed that since Twitter is closer to a near real-time communication medium, it tends to better enable heated debates, even outright textual fights - I've already had to "leave" (no longer follow) one person for this very reason, just to avoid this noise.
Having said all of this, I think there is much realized and future potential with this platform of communication. I think Twitter would benefit from things such as tagging, being able to associate a Tweet with a URL (instead of having to include it in the body of the Tweet), increasing the permitted size of a Tweet to ~250 characters, and the ability to create, join and subscribe Tweet groups. This would allow one to both publish(if a joined member) and subscribe to something like the "ALT.NET Tweet Group" or "Rhino Mocks Tweet Group". Twitter etiquette would encourage people to stay on topic when posting to a group.
Perhaps my suggestions goes against the grain of what Twitter is all about (following people's daily on-goings), but if you think of RSS, it too came from humble beginnings as well - but now we tag, we TrackBack, and we Digg, Kick, etcetera. This has created a very vibrant blog ecosystem, while still maintaining its grassroots heritage.
Regardless, I'm going to stay of Twitter for now - if I continue to see a degradation in the signal-to-noise ratio, I may just tune out...