I've been using iCloud Mail since like 2012 and never felt the need to use any other service, let alone the much uglier (in comparison) Gmail UI!

Besides the ads, Gmail also has that annoying "YourRealAddress+alias" which makes aliases useless, whereas iCloud aliases have saved me from a lot of spam, and it's infinitely better now with their new "Hide My Email" feature that lets you create a different address each time.