I'm not a huge fan, to be honest. And it's mostly for these two reasons:
1. All sales are final. I purchased an iStick 50W from them as a gift and upon receiving it, realized I'd accidentally ordered the version that didn't come with the nice box, USB charger, etc. I contacted MVS to explain the mix up and asked if I could make an exchange. They basically told me I was SOL, so I ended up keeping the iStick for myself and bought the correct version from another vendor.
2. They won't honor 90 day manufacturer warranties. I ended up having a problem with that iStick 50W about 35 days after purchase and while ismoka/eleaf wanted me to handle the warranty exchange through MVS, MVS told me to deal with ismoka directly. A minor inconvenience but if I had it to do all over again, I would've purchased the iStick from a vendor that was willing to address my warranty issue directly.