My two cents, and a buck will get you a cup of coffee someplace but I guess I will chime in:
I can attest to the Compass and Liberty as I have owned both in the last three years. The Compass is overall a nice crossover and offers, agreed, better MPG then the Liberty. The biggest problem I had with my 2007 Compass I had was the lack of "refined interior, but I know that was redone in 2012 and a new Grand Cherokee look to the front end made it my first choice when I went to purchase new last summer. I ended up for financial reasons going with a used 2008 Liberty (my reasons in a moment.) Also I did not like the blind spots and limited cargo room as stated in previous comments but that was not a deal breaker.
The reason I chose the Liberty was because of the towing capabilities and I like to sit higher on the road. I am trying to convince the wife to buy a small camper to get her into the wood more (she is a city girl). Preference also, the Liberty has the "Jeep Look" to me more then the Compass does. The Compass, while nice, had a smaller engine and was a better highway/trip car for MPG, but in all honesty I have almost the same MPG with my Liberty (24/26 best on the highway) as the Compass (28/30). It mostly for me was a matter of preference. I liked the Compass but wanted something different. I liked the Liberty when they first were introduced in the early 2000s but I fell in love with my 2008 redesigned Liberty and I couldn't be happier.
Jeep: It's a passion, not an obsession.
2010 JK Wrangler 2-Door