I know these have been around for a while and they are not the biggest, shinyest, robustest piece of kit but it is the battery/mod I use the most and I would replace in a heartbeat if I lost it.

So on to the pros and cons

Lightweight (easy to carry around and take to work)
Passthrough (perfect for long drives or vaping at a computer desk)
Sprung center post
VV goes from 3 to 6 volts
Digital screen that indicates voltage and battery life
Cheap - $32.90 from the e-cig Mod Shop (for example)
Has a standard ego button (unlike the earlier SLB VV)
Ego and 510 threading

Not really 1200mah more like 950mah
Fatter than a standard ego
Seems a bit flimsy (but has survived my butter fingers and a number of falls on concrete)

So in short. The SLB Mega VV is like the mod you have when you don't need/want an actual mod. Slip it in your pocket and take it to work, take it to the pub, take it on your fishing trip and if you lose it, no biggie.