So it has been a while since I moved our sites from Nucleus CMS to WordPress MU and I an pleased to report that I am on the whole happy.
The migration was a bit rough but WP got the data mostly imported. There was some formatting issues that had to be dealt with though. It is also a bit annoying that normal WP is unable to handle multiple blogs. That is where Nucleus really shined and WP MU is working out. If you are starting out or migrating from a more mainstream system it will be much easier.
I really like the management interface that WP uses it makes Nucleus look like something a middle kid made in the early 2000′s. I also am enjoying the automated upgrades functionality that it offers. Plus there are static pages as well as a sweet iPhone app.
Another nice feature has been that WP can do updates for you. You just put in your FTP or SFTP info and it downloads and installs the update. I would recommend doing a backup, at least of the database, before any update.
The only thing I am not happy about is the theme I chose. I changed it today let me know how you like it. My other gripe is that I have a bunch of drafts that I save, but never bother to edit and publish (this post took 6 months to finally publish).