The assets pipeline feels horrible, it's really slow. I upgraded to Rails 3.1rc, realized it fights with Heroku unless upgrading to the Cedar stack. Lesson learned: stay away from Rails release candidates. But I downgraded to Rails 3.0.8 because 3.1 was just more of a hassle starting out. Maybe I'm doing something wrong, usually when I'm fighting the framework it's a sign that I don't fully understand something. I loved Rails 3.0 when it was announced, but I share the same sentiment as the OP re: 3.1 at the moment.
I've come from PHP, (specifically CodeIgniter) to learning Rails in the last month, and so have focused on learning from the great online Tutorial by Michael Hartl and the rails edgeguides. All are up to 3.0, but I've managed to work fine with 3.1 since I'm an experienced CoffeeScript dev and everything is very well documented in the GitHub commits. I just can't see a cause for complaint.
In regards to the framework being too opinionated and/or moving too fast, its the exact opposite of the landscape in PHP, where there is a splintered and slow moving culture, with no one framework and certainly nothing as technically advanced as Rails.
If I had to pick I'd take the Rails culture everytime, its more exciting and fun for one.
Right, though I think I was more hesitant on upgrading to Cedar--probably could have done that without any problems, but ultimately I just didn't like 3.1rc. My major gripe was with the assets pipeline.
Edit: are images not supposed to be served through /assets? They were loading too slowly for me, that was my major complaint.
I love the 3.1 rcs but using 3rd party css files that reference images are kind of painful to deal with in conjunction with the asset pipeline. I find myself making awkward directory structures in the vendor directory to avoid making modifications to 3rd party css libraries (like jQuery UI). I'm hoping a lot of this will go away when those things are packed into gems that I can just put in my Gemfile and forget. I'm sure Compass and Blueprint will get to that point pretty quickly but I'm not sure that something custom-generated like by jQuery UI ThemeRoller will ever be smooth to set up.
