I've seen some very personal and revealing hubs. As long as you're not violating someone else's privacy or going against site guidelines, personal hubs are acceptable. Just avoid anything that would be more appropriate for a blog. The site does not consider blogs to be the type of content they prefer.
As for opinion vs facts - make sure the reader understands which is which. People often take online content to be gospel, and it's important to make a distinction. You can pose opinions in the form of questions (What if? Or 'should we consider?) to get people thinking.