I've had my new 2010 Mariner Hybrid now for a couple of weeks and I have absolutely no buyer's remorse whatsoever! I love it! I'm averaging close to 34mpg (highway and street combined). The ride is smooth, great visibility, love the NAV system and sync features. "So far" ... worth every penny I spent for it!
Engine (great pep for 4 cylinders!), NAV system, layout of console, etc.
Could provide "a little more" head room (I'm close to 6'2"). Could cut down on the sound of the engine a little under hard acceleration -- but it's like a monastery compared to my old Explorer!