I've been working with GG for the past 3 months or so. It's a great network for MVAS offers. They have daily payments and a lot of different payment methods available. Many of the offers are very good (higher payouts and conversion rates than similar networks).
Some of the not so perfect things: no API, if the offer has a cap you won't know until you hit it, slight communication barrier because the AMs main language isn't English, and the UI can take some time to get used to.