I've had my 2014 Summit for a little over a week and about 500 miles. I had thought the differences wouldn't be that great and was kinda questioning my decision to jump to a 2014 with only 24,000 on my 2011.
But I have to say after driving the 2014 Summit for a week, I am very very pleased with my decision. The 8-speed transmission is wonderful, HUGE change from the 2011...HUGE. I know someone had said that the transmission alone would be worth it and, well, that's pretty close to the truth. So smooth and responsive (I have yet to try out the paddle shifters though...kinda trying to figure why I would even need them in normal driving). The V8 seems more responsive and powerful with this transmission.
The exterior cosmetic changes are very nice and I even like the rims now that I have it in person. Love the adaptive headlights and the lights in general. Headlight washers seem to be pretty strong as they create clouds of mist. I like the changes so much I am like "flipper glass, what flipper glass?" LOL.
The cabin interior is A+. I noticed the steering wheel seems to be a tad smaller in diameter and the wood is less and more leather (I actually took photos of the 2011 and 2014 to compare)....don't know if good or bad. Also, the wood has grooves (finger bumps or whatever they are called) on the backside of the steering wheel...a very subtle difference but I guess people must like that. The buttons on the steering wheel have a better layout too.
The cabin is definitely much quieter - noticeable right away. Must be a combination of things not the least of which is the heavier matching suede headliner and pillars. In addition, the upper leather matches the lower plastic incredibly well...I had the door open in the sunlight and you could barely tell the difference --- same color and texture. Excellent match.
The seats seem to be a bit denser too and without a doubt the leather is a more premium leather (although the 2011 leather was more than acceptable, the 2014 leather is just better). There is a greater attention to detail in the cabin finishes overall. I really do like the Grand Canyon Jeep Brown so I am glad I made that choice...I don't miss my New Saddle / Black interior anymore.
The "radio" unit is also a big step up. Again, I didn't think it would be that big of a deal, but it was more substantial than I thought it would be. I pretty much like everything about it so far. The nav system took a bit of getting used to since my old 730N had a "simpler" nav experience but not as informative. The stereo and speaker system is also a huge step up, very very very nice. The bluetooth connectivity with my iPhone 5s is also much better for controlling the iPhone via bluetooth.
The A/C seems colder although take a second or two longer to kick in or at least that is my perception. The ventilated seats (at least the driver's side) doesn't seem to be as noticeable so I am going to take a closer look to make sure all is OK with it.
Everything seems to be solid and tight and the 2014 is a tighter, more responsive driving experience overall.
So, yes, the 2014 has made substantial improvements over the 2011 and I am glad I made the jump even though it wasn't inexpensive to do so.