The vertical coil is harder to make, look at the bends with the included wire. Getting past that, wicking around the vertical coil is harder and time consuming. Since I did not notice anything superior in the vape, didn't seem worth the added time and trouble. BIGGEST PLUS of making horizontal coil, is when you want to rewick. Pull out the old wick, slide a new one in. With a vertical, you have to pull the entire coil out and start the rewick process again. Might be worth the effort if you decide the vertical offers something over the horizontal, but I did not. Play with both, and then decide.
Do however READ the little included manual, as well as some YouTube videos. When you make a horizontal coil, you need to add some wicking to the very bottom of the RBA, which you don't need to do on the vertical build.
It's not a great RBA, could have been better if they did not try and accommodate both vert and horz styles, used a better capture screw, and used two posts like the STM RBA. It's better then not having an RBA, but once I can find the Cubis titanium prebuilts, I doubt I'll be using the RBA much, at $8-10 for a 5 pack of coils it's just easy and convenient.