a) Yet another layer of government, who is going to pay for it?
(linked to)
b) What is the point of another powerless talking shop?
(separate from)
c) Stirred fears in local councils that they were going to lose powers to the body.
d) Played on "national spirit" suggesting that what was really needed was an English parliament, not anything more regional.
That's about it really. The biggest factor was that there is a whole set of people in the UK who are very distrustful and disdainful of politicians and the No campaing was able to frame the idea as: "Do you want more of your money taken from you in taxes to pay another set of politicians in Newcastle/York/etc."
The Yes camp were useless, but the proposals were pretty weak too. Control freaks at Westminister were not willing to give the local assemblies enough powers to make them viable.