For me the biggest advantage to running NetBSD on x86 is that it includes many of the features of other BSDs (simplicity, documentation, PF, CARP, etc..) and it runs great as a Xen Dom0/DomU.
Because NetBSD runs so well as a domU I'm really surprised it's not much more popular at many of the larger Xen-based cloud hosting platforms. I've heard it also works well with KVM & virtio but never tired it myself.
I just tried it on RHEVH the other week, and it -runs- well (easy to setup, just works, virtio works as expected), but on shutdown, would jump to kernel debugger.
I didn't get shutdown issue sorted, or benchmark performance, but it's really easy to setup and start playing with.
Because NetBSD runs so well as a domU I'm really surprised it's not much more popular at many of the larger Xen-based cloud hosting platforms. I've heard it also works well with KVM & virtio but never tired it myself.