Oh wow, most people I've spoken to have never heard of it before, then 4 come along at once! Y'all are like buses :p
It's not as impenetrable for a newbie as it looks. When the blues invaded us the 4 of us who just got into it were all L1 and they planted L8 (max level) resonators everywhere. Between us we got the town back to fully green in about 3-4 days. Solo I reckon I could've done it in a week (but I couldn't solo if I tried, everyone keeps seeing it and joining in :p). I'm almost level 4 now, too, after a week at it.
Good for basic exercise.. it's got my daily average steps up from 4000 to 6000 (keep in mind before saying "lol is that all, I do 20k every morning" that I'm sat at a desk all day for my job and don't get much time on an evening) and got me several places I can't normally be bothered to walk to like a monument up a pretty steep hill :p
I did actually find someone playing Ingress right beside me. On my side. I was there hacking a portal by a church when someone else wandered up prodding at his phone in a similar fashion, then we just kind of looked at each other "are you...?" "yup!" - he turned out to be one of the guys I'd noticed on the chat.
One of my mates drove a fair distance to put a huge triangle up. It was taken down half a day later. Lesson learned, don't waste fuel playing this thing xD Tis a walking game!