"In cases when the risk analysis engine can't confidently predict whether a user is a human or an abusive agent, it will prompt a CAPTCHA to elicit more cues"
So if you have cookies disabled, you'll probably just get a regular captcha
Just ask anyone older enough to have worked with Microsoft et all in the past.
yeah, the company is nice now, but nobody can say anything about tomorrow. So do you their sane offerings, but be aware that you may have to be on the line to change it at a moments notice. and try to not depend on it too much. (i.e. always have a 1% bucket with an alternative solution, least you find yourself locked in when you 'thought' you had an alternative if you 'needed')
However, looking from a different perspective you can say that they're taking advantage of people blind with greed who want maximum convenience when using the web.