The tips, ads, and recommendations you see will be more generic and may be less relevant to you.
And this is treated as a bad thing?!
The number of ads you see won't change, but they may be less relevant to you.
Send only info about your device, its settings and capabilities, and whether it is performing properly.
In other words, even after turning off all the settings, your data still gets collected.
The rest of the installation process wasn't fun either. It was worded in this weird, condescending tone, like "Let's get everything set up for you", and "Let Cortana help you get things done!".
Thank goodness for FLOSS and GNU/Linux.