I have had a go-go for about 10 days, and I vape "heavily". Its a good, solid, PV and the cartos are easy to refill. I've been switching between 2 of them (for flavor changes) and top them off once, maybe twice a day. The batteries are great and the flavor is, well, about the same as any of my other cartos. Just a LOT more capacity. Only downside I see is you need something else for testing new flavors, 3ml is a lot of juice I'm not too worried about the proprietary aspect, they seem to be quite popular already and I've heard a few of the vendors are looking into making a 510 adapter.