I'm really enjoying my Vivi Nova so far.. actually the minis are what I use most often. I have both styles. I have to fill the minis more often, but I'll take the trade-off for the sleeker look with my spinner battery.
They can be a bit fiddly. If you dropped it by accident, the center post can get out of alignment, leading to flooding and leaking through the center post. A little tweaking will get you back into shape.
If all the internal parts are aligned correctly, you should be able to store the Nova in a horizontal fashion without flooding, and you'll find your stock wicks will soak up juice better that way.
I'm going to take the next step and get some resistance wire and cotton wicks and roll my own. I hear that the cotton wicks suck up juice like crazy, and makes an improvement in flavor, so I want to check that out.
I have found that some e-juice does fall a bit flat in the Nova... but currently I'm digging on butterscotch flavors, and the two samples I got from two different outfits are hitting like a champ and leave me very satisfied

It's the sweeter fruit flavors I found that didn't transfer all that well... but then it could have been the juice and the PG/VG ratio. I vape a 70/30 PG/VG respectively.
I'm sort of going on in this post, but I hope it is helpful in some way.