They're easy to use, clean too. Just unscrew the empty cartridge and screw in the new and away you go, easy. Flavours are good, I have a preference for the cherry or berry one.
I also have a vype pebble, love this a lot, but unfortunately, although I'm on my third, they seem to give up on me, latest one carries on heating the fluid even when it is between inhalations. I won't give up on it though, feels great in my hand and gives an excellent hit.