I watched the entire game on YouTube yesterday, had it on in the background while I was doing some work on my computer. I'd say you pretty much nailed it.
Major ending spoiler for anyone who doesn't care about such things. DOUBLE spoiler block just to prevent accidents. If you're going to quote this post, please make sure the spoiler blocks are preserved.
The chapter 4 boss is exactly the same as the final boss. QTE's and all. Yeahhhhh...
@mb: It was already answered multiple times so I didn't feel the need to say the exact same thing, but it's a weird complaint to complain about a free weekend title being added temporarily to your list. Now if they added every F2P game in the steam database to your account, that'd defintly be a legit complaint.
Perhaps you should read the question again.
In the future if you're just going to pop into a thread to complain about it or make an entirely unhelpful comment such as the one in this topic, do us all a favor and just don't.