Now that I've had my vp-901 for a good few days, here are my initial thoughts.
It's just what I needed. Small footprint, replaceable batteries, and a nice design.
It lasts about 4-6 times longer than my crappy 901 batteries.
2 batteries usually last more than all day (I had 6 901 batts in rotation before).
Build construction is solid.
Vapor production is slightly better than a perfect fully charged stock battery.
Vapor does NOT taste burnt, unlike usb adapters I have used (hence why I went for a 3.7v solution).
Additionally, customer service has been VERY responsive. The 1st one off the block had a small defect and they were very fast to respond and replace.
I'll post more after I've had it for awhile. So far though, I'm digging it.

It's just what I needed. Small footprint, replaceable batteries, and a nice design.
It lasts about 4-6 times longer than my crappy 901 batteries.
2 batteries usually last more than all day (I had 6 901 batts in rotation before).
Build construction is solid.
Vapor production is slightly better than a perfect fully charged stock battery.
Vapor does NOT taste burnt, unlike usb adapters I have used (hence why I went for a 3.7v solution).
Additionally, customer service has been VERY responsive. The 1st one off the block had a small defect and they were very fast to respond and replace.
I'll post more after I've had it for awhile. So far though, I'm digging it.
