StatusNet has many strengths. It's design keeps users coming back for more, and it's architecture around OAuth lets administrators of sites let users connect their posts on twitter to a StatusNet website. Users can also get instantly updated feeds, and can communicate easily with users of the site, creating a healthy community. Best of all, it's free.
I found it hard to update. As a matter of fact, when a new version was released, I couldn't update it at all! If you only want a small site, then this is a good choice for you. If you want a large scale site, you might want to hire a large scale of developers to get down to business and do the dirty work for you. All in all, that's it's only weakness.
I am the admin here, and I have to report, it's got a clean slate. It has all it's features completely lined up, and it also has it's own avatar interface, along with most popular posts on the side of the screen. It's like an all-in-one twitter-competitor waiting to happen. Extremely good job on that, Status.Net!