Why photoetched parts require "advanced" modelling technique?

I'm new to modelling and glad I've found this site. I've got another question.
I've read some faqs here and there, and most people say photoetch kits are for advanced model builders. Can you tell me why is that?? I've ordered a S27 PE kit for my Tamiya Nissan 350Z kit (thanks for a fellow member for the recommendation on the S27 kit). I haven't started building it yet. I don't wanna screw up on this one I really like.
All I see is just a sheet of thin metal that needs to be pasted on the model. So why does everyone say it requires advanced skills? What are the things that I should look out for?

PS: I've read the faq here about using spray adhesive, or clear acrylic colour for glue.

I wouldn't exactly say you 'just paste' the parts on the models, there's a lot more to it than that.
The parts are small and you have to be careful handling them, not only that but some will require bending and folding.

Maybe once you have the parts in your hands you'll understand better.