my only complaint would be that the mechanism that holds the metal screw part in to the battery is not made very well and breaks... I have just bought my third vype epen due to the first 2 breaking in the same way - The screw in part becomes detached from the battery, you can put it back in with some difficulty, but once it comes out once, it will fall out again. This is due to the removal action being a twist, so after a while, when twisting new cartridges or the charger on and off, the piece comes out. Eventually, one of the wires snaps and then it is game over and time to buy another :( If this happens to my new epen, I will likely look for another brand. Other than that - great product, nice flavours (love the new smooth virginia tasting flavour) good charge time, etc...