Pangur, it really depends, on the school and the department.
Its actually a good thing there are lots of resources there already as making lessons from scratch is time consuming.
In my school, there are lessons there but they're a, guide to use and to be used for ideas and as a, template.
I find this thread a little annoying causes its like someone asking should they buy chocolate ice cream and then everyone saying they shouldn't cause they don't like it.
All schools are different. Harris works for some people, and not for others. You have to just go and find out for yourself. I persoanlly like it and know dozens of happy satisfied teachers, I also know some who hated it and left. Like chocolate ice cream, it isn't for everyone, and asking a thread isn't going to get you your answer.
You need to taste if yourself.
It would be sad you miss out and a happy and successful career because of a few people on a website, that's all.
I suggest going and checking it out and make your own mind up.
Also, I tend to find that on forums etc you get a Lot of negativity about teaching generally.
Frankly, because the happy teachers have better things to be doing than going online and moaning about the profession.