The Mercedes is expensive to maintain and doesn't hold it's value well without the diesel offering - not to mention it is about as exciting to drive as an old Oldsmobile station wagon.
Having just swapped a 2011 GL350 for a 2015 SR5 Premium I can confirm all this. If you want to pay for a new GL under warranty you're probably fine, but there's so much tech/sensors going on that >100,000km you're looking at a steady stream of "minor" but not necessarily inexpensive replacement parts (i.e. LED side view mirrors, parking sensors x8, etc.)... plus there are some bigger issues that plague the GLs (oil coolant seal leaks, air suspension leaks). Maybe the newer models have addressed these, but they are $$$ to deal with and can cascade into bigger issues. MB Diesel reputation for "bulletproof" quality was lost probably a decade ago.
The GL was well designed (layout, functionality) and for a full-size vehicle to get 9-10 L/100km highway (could go 1,000km per tank loaded and with a roof box). It was a dream on long roadtrips. Technically capable off-road, but a vehicle that size needed to be on wide, low profile street rubber... and no spare tire! (diesels only)
I never thought I'd say it, but keyless entry/push button start is super convenient, as is a remote back hatch, driver seat position memory, and auto headlights. As many here have been saying - these seem like very simple improvements that could've made to the 4Runner years ago. Other tech, like parking sensors, dual/auto climate control, auto wipers are more trouble than their worth IMO. And for a true off-road capable rig, I think most of us would be willing to sacrifice fuel efficiency, on road handling and even some of the advanced safety features that are out now.
The review is pretty accurate... It's what the average C&D reader probably needs to hear.