A friend of mine had one he bought new. Its a Motori diesel engine from Italy. They are kind of nice but don't get great economy. It would struggle to get 25-26mpg even with emissions deleted. Mostly a low 20s mpg. It did have some warranty issues too but I don't remember off the top of my head what they were. For a few years I had an '07 Liberty with the gas V6 and it sucked. Low power, low economy, and started to have issues at 75k miles. It also had a power window problem that kept coming back so much that Jeep extended the warranty for that window for a lifetime. And it still broke again.
We traded it in for out '14 Dart and was happy to see it go. I don't think its a horrible car but I'd say its sure not the greatest either. For example, the new Darts have a pretty horrible reputation for being junk but we have 90k on ours and absolutely love it. It's been great. Maybe the Liberty is the same way. I'd do a thorough check on it and lots of research before I bought one though.
Oh, I was going to add, they only made them for a couple of years so parts are probably hard to find too.