I guess it's all relative. If you're comparing Wordpress.org (self-hosted) with building your own site from scratch, it's a
lot easier. If you're comparing it with Blogger, Wordpress.org is harder.
Thesis is great. It saves me a lot of time customizing and
seo'ing. It does have a learning curve though for customizing - but it's a lot
less work than doing it from scratch. Thesis has control panel areas where you can easily set a lot of things, a very helpful forum and several how-to areas. I hear Headway is very good as well.
I haven't used any other themes, but a friend tells me that the free ones she's tried have been a lot harder to customize. It depends on what level of customizing you want to do I guess.
I agree with Renee. Nothing is easy when you don't know how it works. In my opinion though, Wordpress is so worth the initial effort.
Deb