Battery life is supposed to be excellent[1]. TL;DR 15+ hours of light usage for the 1080p screen (tested and confirmed by Anandtech), supposedly 11+ hours light usage for the QHD+ screen with an i7.
I have a maxxed out XPS 13 and its a love-hate relationship. The screen and build quality is great, the keyboard ok and the touchpad as well. There's very little to match it in that form factor right now
It's noisy as hell though, I can't say that battery life is great and I have some weird problems with music stuttering when I compile, also Visual Studio ocassionally locks up on deploy for some reason.
If I could have a Zenbook with the same screen thought I'd take that any day.
Also, I notice that this XPS is 0.6-0.8 pounds heavier than the new MacBook, and as far as I can tell the XPS has a fan.