YouTube, seriously, stop changing the channels. Stop messing around with the layouts and sending everything completely out of whack. It hasn’t even been that long since you forced everyone to switch to the most recent design, which required most people to have to redesign their banner and/or background to fit the new layout.
The first big problem I see with this layout is the severe lack of customisation by way of images/backgrounds. There is one cover photo location, and that’s it. And to make matters worse, this cover image isn’t even showing up on the example channels you linked to, which doesn’t help to showcase to people what can be done! I don’t know what that cover section looks like when not on a computer, but it really needs to have the option to drastically increase the height. Current height says it’s 175px high, it should be at least 250px.
I also dislike that there’s not an easily accessible text information box available on the main landing page to describe what your channel is about – other than the “trailer” video that will be present in the main video spotlight to non-subscribers. If you’re going to stick with the trailer concept, at least be nice enough to not truncate the description to allow creators to post what they want to be seen there!
While it’s nice that social media and external site links are available in the header, they are far too small and not noticeable. Again, I can’t say what they will look like when a cover is actually there because... well, there’s no cover there to compare with.
The Discussion tab is improperly named, as it’s just the channel comments page. When I see the word “discussion”, I expect there to be something not unlike a mini-forum – or if anything, just some threaded comments – at least some mechanism for proper related discussion rather than a long list of incoherent messages.
My final gripe is with the whole left-hand Guide itself – I have to use Stylish to get rid of the guide so that I can extend the video player out to 720p to watch on my secondary monitor, which is only 1440×900. I wish this could be done natively without having to hack...
Not sure if there’s much else I want to rant about it, but my god, it really does suck.