Too good, in fact: it won't run on any laptops that I own because their GPUs don't support a sufficient level of OpenGL.
One great aspect of Firefox-with-Gecko is that you can throw it onto just about any machine with more than 512MB of RAM and it will provide bootstrap web access ( slow or otherwise ). That's going to be lost when everything is Servoised. I guess it's back to links2 at that point.
For ease of development, webrender2 is configured to compile with the latest OpenGl 4.x features. I believe there is a way to build it to target a lower OpenGl version.
Edit: Correction, its currently targeted at OpenGl 3.2. There's an open issue for bringing it down to OpenGl 3.1 which is the version supported by integrated Sandybridge GPUs. Considering 40% of people running Intel are using Sandybridge or older, that's probably why it wont run on your laptops.
Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller
OpenGL renderer string: Mesa DRI Intel(R) 965GM
Maximum OpenGL version for that chipset is 2.0, apparently, though I can't find a way to push it beyond 1.4 on Linux
I appreciate that six years old is ancient by SV standards but I would be interested to learn what proportion of Firefox users are on equally old hardware. I did try launching Servo with CPU rendering but it hung indefinitely.
I don't think the software fallback has gotten much love but AFAIK it'll work fine once llvmpipe support is added to webrender2 [1]. Once that is done, rendering will work with the vast majority of laptops and desktops running Linux/MacOS/Windows. The OpenGL version supported by that chipset is over a decade old so devoting time to compatibility this early in the project would be a waste of time (and defeat the purpose since the standard predates the explosion of mobile devices).
EDIT: to be clear, with the Servo nightlies you need to do this yourself but Firefox could bundle it eventually.