Using it right now from Concourse B. It's definately a bit pokey, feels something like a 56k modem connection.

Ads:

One full-page redirect ad on initial connect, the "continue to connection" button appears and brings up the "agree to terms" page.

In-page ads - the system redirects your page into a frame with an ad approx. 150px tall on the top of the page, but only about 50% of the time. the rest of the time your site appears full screen. Takes up a bit of real estate but it's not terrible.

Overall annoyance factor - pretty low.