Personally, I do think we should be able to install whatever stores or apps we want, on whatever device. If I buy an iPhone, it becomes mine. It's my property, not Apple's, and they shouldn't have any further say in what I'm allowed to run on it. I understand that this would disrupt the market, and there might be some significant changes. But I see the control of our devices as an important issue. If it was up to me, I'd go through with this, or something similar.
Having this only apply if there's a userbase of 50 million people or more does strike me as arbitrary. Companies would be allowed to have a completely different model, as long as they try to keep their userbase stable at 40 million or so and not grow further. Would that actually happen? I have no idea. But the potential exists, and it would be weird.
I'm also still a little iffy about that one part of Section 3, about enforcing a payment system. There's a way I could interpret that which I wouldn't be a fan of, but there's just enough ambiguity that I'm second guessing myself. And I can live with the rest of the bill, for sure.