Hmmm. I must be doing something wrong, because I feel like it's completely unstable for me. NUC6i5 with integrated Iris on Ubuntu 16.04. I get a dozen errors a day with the x server, and I get weird intermittent visual glitches with multiple monitors.
I have no need for high performance and Iris should be good enough, but the stability still leaves a lot to be desired.
Ubuntu 16.04 is pretty old code. I would try a mainline kernel (currently http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.11.3/) and maybe even more up to date userspace libraries (but then you're getting into a dependency mess. replacing just the kernel is easy).
I have no need for high performance and Iris should be good enough, but the stability still leaves a lot to be desired.