i had Insider about 16 months ago. Initially, there were no ads. Over time, a few ads started appearing, but they could be switched off in the settings. In the last month or so, there were still a few ads (interstitials IIRC) that couldn't be disabled.
The only thing that made Insider worth it was the Life in Japan bits and the occasional video. E3 is the only time i'd consider getting another premium account, but it would probably be with Gamespot.