Don't take this too negatively, though. Core M is no Atom (although I have seen some numbers dip to the point where a desktop Atom can defeat it). For most of the tasks people use ultra portable laptops for, you won't be able to tell it from a Core i5 or Core i7 CPU.
For a final judgement on cross-platform performance we'll have to wait to get a new MacBook. The real sticky question: Is it even fair to a fanless notebook against one that's actively cooled? My gut says the Dell XPS13 will easily be all over the 12-inch MacBook from a performance perspective. But it has a fan that makes its presence known.
Battery life and capacity
One of the 12-inch MacBook's more unique touches is its batteries, which Apple claims to have built up in layers. Terracing the battery packs lets the company jam the maximum physical amount of battery capacity into the shell.
By the raw numbers, it seems to have worked. The 11-inch MacBook Air has a 38 watt hour cell in it. The much thinner and lighter 12-inch MacBook has 39.7 watt hour cell. Combined with the Core M chip, Apple claims it'll give you 9 hours of browsing and 10 hours of iTunes movies. (Who really uses iTunes to watch movies?). That's the same browsing rating as the MacBook Air 11, and the one hour more in movie playback. You may say meh, but remember: The new MacBook packs a significant increase in resolution.
The original MacBook Air essentially has a 1 megapixel display at 1366x768. The new MacBook basically has triple its pixel count, yet slightly more battery life.
What about compared to PCs? Well, that's not easy to do, and if you do, people will just choose to disagree. I can say that in run time, PC's can hang--but everyone's mileage will vary depending on what he or she does.
But you still want to know what PC's are powered by so I'll tell you: The Zenbook UX305 packs in a 45 watt hour battery while the XPS13 is running a 52 watt hour job. HP's new Spectre x360 runs a 56 watt hour cell.
Now onto the most controversial decision Apple made with the new MacBook. There's but a single USB 3.1 Type-C reversible USB connector on the laptop, along with a combo analog audio port. There's no HDMI, no Ethernet, no SD card slot--nothing else whatsoever. Maybe this is my personal bias but give Apple credit for taking what would be seen as a limitation on a PC and turning it into a strength:
"Only one USB port and HDMI port on this ultrabook?! You suck, vendor X."
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