Old story. Have a look at
https://mail-index.netbsd.org/current-users/2013/04/24/msg022584.html .
Basically you have to disable ACPI and SMP (stop to boot prompt and do 'boot netbsd -12). Nevertheless the emulated Tulip is not that great, and with SMP not working the options become less and less.
FreeBSD 10.1 has Hyper-V support out of the box; Freebsd 9.3 - after a minor setup. I guess the issue is not that important for NetBSD development, porting of the whole FreeBSD suite would not be trivial as far as I can see it.
I can try -current later.
Chavdar Ivanov