What are the trillion other problems? Honest question, some I heard this a lot, but in reality I only ever saw people complain about the speed of the filesystem. So that would just mean 1 (hard) thing to fix.
The network stack integration was less than transparent too. Random places all over the system where e.g. a magical ioctl() just didn't work properly. Who really wants to spend their life reimplementing every last baroque detail of that stuff?