I'm very pleased with the wk. Im still a bit old fashioned and worry about the number of electrical switches compared to the WJs (eg for engaging 4wd low...where the wj has a lever the wk has a button), but to be fair it's the way everything is now, and the wk is still relatively unrefined / less electrically dependent /more of a workhorse than the more road biased competitors (x5's RRsport etc).... But that's what I need. The ride is much improved to the wj, the circa 220bhp 3.0 Mercedes power train very strong (and surprisingly quick when not towing). My wife likes driving it too. I haven't had to buy anything as yet aside service items, but parts are readily available. It's also on a timing chain.
It's Quadra Trac 11, so very good in sand / mud (I'm a big fan as you may have seen on previous posts, you always get an armchair expert who'll tell you old fashioned locking diffs are better etc...... In the right hands I'm sure they are, I've had air lockers on one of my defenders.....but the jeep system copes very well without any dramas /flatters the driver.....and is still electronics light compared to many alternative / modern systems.
It tows 3.5 tonnes capably, it's comfortable, it's probably as reliable as anything else out there, they're very cheap compared to anything green oval of similar vintage....
I'm also quietly looking for another one at the moment to replace one of the other WJs.... Eventually I'll replace the three WJs for 3 WKs. Hope that helps?