What do you like best?
Xara Xtreme is a very complete software and you can use it for everything... from diagraming to prototyping to vector drawing and specially useful to make wireframes.
It easily becomes your primary designing tool and the speeds up your workflow in an incredible way.
One of the things I enjoy the most is the auto-backup and versioning, which both saved me more than once.
What do you dislike?
The only thing I had against it was the web export. The code generated is really terrible and unpractical.
I also don't like not being able to automatically generate multiple guide lines by entering percentages (ie: dividing the page in 3... like it's easy to do in Adobe InDesign).
Recommendations to others considering the product
First, you have to understand that the current Xara Xtreme is an open-source project based on a 2006 Xara product that was then divided into multiple, smaller and specialized products plus a new complete suite called Xara Designer Pro.
If you're using Linux, go for the current Xara Xtreme without doubts... but if you use Windows, think about why do you need it and then go for Xara website and decide which product is better for you: one of the smaller ones or the full suite.
If you're a professional graphic designer or a web designer, I recommend going straight to Xara Designer Pro.
What business problems are you solving with the product? What benefits have you realized?
As said earlier, you can use it for everything: diagraming, prototyping, graphic design, branding, cover design, vector drawing, wireframes... simply everything.
I've been using Xara Xtreme Pro and later the upgraded Xara Designer Pro for over 7 years now as my primary design tool.