Excellent review, as always, NBR! This new Dell XPS-13 is one of those head-turners that is making a splash everywhere because of its design language combined with apparently very good ultrabook level of performance. Here's the problem - and it's not unique to this model or to Dell products; especially vulnerable are also Asus and Lenovo Thinkpad in the past 2 years - poor design/quality control resulting in numerous ownership headaches after the product has been purchased, put through its paces when first arriving and then put to daily use, much of it with fairly high heat inside this tiny case with little ability to dissipate it, the notebook will begin to fail. The same was true of its predecessor, the Dell XPS-15, several celebrated Asus models, most notably the UX31A, and, to the shock of many, stalwart Thinkpad models such as the T440s, T540, X240. Just read the owner forums of these manufacturers specific to owners of these (and other) models. Look also in independent forums, such as notebookreview.com and in the owner review sections of Amazon and other vendors who sell large volumes and accumulate hundreds if not thousands of individual reviews for popular models such as this Dell XPS13 is certain to be.
Pure conjecture on my part, but it is the drive towards increasingly thin cases that probably causes most of the problems. The throttling and fan designs may keep the products from shutting down due to heat or becoming too hot to touch on the outside, but even temps which fall within Intel's and others' specs cause an oven environment in which all of those components have to live, all the time. Add to this the extremely spotty customer support offered by these brands, depending upon the country and the warranty plan one purchases. By and large the quality of Dell's and Lenovo's support has been plummeting in the US while Asus has long been in the cellar. If you read the Amazon owner reviews seething with hateful frustration with Asus for its horrific quality control of the seductively positioned UX31A second gen Ultrabook and superimpose them over the glowing reviews NBR provided for the same model that people replaced 2 and 3 times before giving up you'll swear we're looking at two entirely different computers. The same is true famously of the Thinkpad 440s and for all of the XPS models of the past two years.
I don't know exactly how a highly conscientious testing shop like NBR protects itself from providing glowing reviews and what amount to screaming "buy" recommendations without either doing their own owner surveys - a costly endeavor - or perhaps teaming with those who do or, at a minimum, citing and linking to the average owner ratings on Amazon.com. It's long been said that unhappy buyers are over-represented on such forums, but that doesn't account for the existence of a large number of products that have 4.8/5.0 stars (96%) with hundreds of reviews while some models rated 85 or better by NBR skate by with about 3/5 stars (60%)among hundreds and hundreds of reviewers on Amazon. (Interestingly, if you look at the distribution of ratings for the low average models, they tend to cluster with 1* ratings and 5* ratings, representing the hit-or-miss quality control and, I can only conjecture because I haven't studied it, likely those who rated their purchase on the first day or two of ownership vs. those who waited until they had weeks or months of usage experience. One last comment: Back when they had not overcome the terrible design/reliability problems they have now largely surmounted, Jaguar automobiles were consistently given accolades by those who reviewed them, even though most knew they would be headaches and major expenses for their owners. Somehow I feel that product reviews, especially those that convey implicit "buy" recommendations, must at a minimum provide readers with tools to check the ownership experience of models they praise.