Well, what are pros and cons?

If I understand it right, the packages in "Universe" area are not checked by Ubuntu stuff for compartibility. But there are some packages that I need to use from outside of what Ubuntu offer. For example, my MUA is Sylpheed which Ubuntu don't have. I got it from Debian's unstable tree by including Debian's link in sources.list. But if possible, I would like to keep exclusive to Ubuntu's links. I also know that currently, there are npo packages list like what Debian have for Ubuntu but it's in the works.

So, what's in "Universe" area of Ubuntu? I don't like to screw this box up with something I don't know. Educate me, please.