The ads thing can be opted out of if you chooses default as well. It's a bit of a fiddle, but doable. It wasn't an auto download for 8.1 unless you reserved your copy for it, and you had to go through a different procedure to get it, as opposed to it being in the general updates page.
Or google the opt out thing as well.
I've installed it on my new laptop and had one issue with it and thats because I didn't pay attention to when I installed it, and that was because it was in Japanese, I accidentally accepted default install. And it likes to reinstall apps I take out. I'd really like to delete forever some apps (never going to use the xboxx app for example).
I like it more than 8.1, but overall, I think Win7 is better than both. So if you're on 8/8.1, do it. If win7, I'd stick with that![]()