The downside is that it's quite a bit different from (and imo a bit worse than) the other books and could mislead you about what the series is like - or even turn you off entirely.
If you're already committed to reading the entire series, I'd start with Consider Phlebas. If you're unsure, start with The Player of Games.
The problem is that you feel you have an intrinsic right to the content. Like the content is a public good, and youtube shimmied it's way inbetween so it can shove ads in your face.
But that is not what the deal is. The content is made by creators explicity for youtube, and you are the one making a decision to go to youtube to view privately owned content that you have zero right to.
YT didn't have to build their platform on the web. Nobody forced them to. They could avoid all of these issues by setting up a dedicated client application using a custom protocol with ads already baked into the video stream, for example.
I don't feel like I have an intrinsic right to any content on YT. But I do feel like I have an intrinsic right to use the web the way it's supposed to be used. Which, of course, includes simply ignoring any HTML, CSS, JS or other bits that I don't like. I'm free to send whatever HTTP requests I want to YT, YT is free to respond with whatever they want and I'm free to do whatever I want with their responses. That's just how it is.
If YT doesn't like that... again, nobody is forcing them to use the WWW. They are free to use some locked down technology that better fits their specific needs.
Claiming that I am morally obligated to look at ads on YT is like claiming that I'm morally obligated to look at ads in a print magazine. I hold the magazine in my hands. I flip the pages. I guide my eyes towards the things I want to look at and away from the things I don't want to look at. This is not a surprise to anyone, it's just how reading a magazine works. Same thing with YT ads and the WWW.