While we've already established that Pokemon Go [Free] is on track to be bigger than sliced bread, not everything is as awesome as it seems in the land of Pokemon. As discovered by Adam Reeve, principal architect of the security firm RedOwl, if you're playing Pokemon Go via logging in through your Google Account, you're potentially giving Niantic and Pokemon Go access to everything on your Google account. What can you do with full access to a Google account" Well, as Reeve points out:
Let me be clear - Pokemon Go and Niantic can now:

Read all your email
Send email as you
Access all your Google drive documents (including deleting them)
Look at your search history and your Maps navigation history
Access any private photos you may store in Google Photos And a whole lot more

Sure enough, I double checked my own Google Account, and Pokemon Go has full access to everything. Oddly enough, Niantic's other game, Ingress [Free], which also uses your Google account only requests permission to basic account info:

The other option for playing on iOS is by using a Club Pokemon account, but it seems the whole Club Pokemon system has been offline ever since Pokemon Go got slammed so hard. Also, there doesn't appear to be any way to transition from a Google account to a Club Pokemon account, as your progress is locked to your account. Right now, this is all feeling kind of gross as Google really ties you into their ecosystem and I really, really don't like the idea that Pokemon Go ...