On the main homepage instead of showing your subscriptions with recommended videos down the side, they are all in one stream. This is extremely annoying because now I need to click a separate button to see the content I'm interested in.
The old YouTube was quite colourful as it used black, red and white to define and enhance columns and words. This new YouTube is a lot more black and white which was probably to make the site look 'cleaner' however in truth it is just more confusing.
One thing which is also bugging me about it is how the whole page is slightly to the left of the screen instead of in the middle. For some reason, the owners of YouTube, Google, obviously think it is good to have a big white margin on the right hand side of your screen.
I'll admit there are some good points in this new YouTube such as that if you are looking for a specific video and you click on a video but discover it is not the one you are looking for, your other search results are displayed on the left side of the page so you can just select one of them.