I understand Canonicals intentions: with everything going "cloud" and "online" it makes total sense to offer just one search box instead of two. It's easy, it's convenient.

However it sends your input to a third party or maybe parties in the future. You no longer control your data. Is it even encrypted? Who can see what you are searching? Your family, your provider, everybody on your wifi?

It's not about ads in the first place, it's about data protection, trust and user interfaces.

However this isn't Ubunut, this is just Canonical Unity. I'd just install gnome-shell/kde/xfce/... and be done with it.