The vertical panels are bifacial so they get some of the light being reflected from the other side. This is a huge boost to their productivity.
The other major advantage here is that you can use them with farming and actually do something with the space.
In addition areas where it snows sees a dramatic uptick in solar power because of the reflection of the snow and not needing to brush the panels off.
vertical panel layouts really open up a LOT of options that were not available before. (using them as fences, putting them on sun facing walls of homes spaced off and letting the pass through sunlight hit the other side). There's a lot of possibilities here).
The benefit of vertical is that it produces a duck-curve. The normal cosine curve with a peak at noon is basically the inverse of grid-scale demand, which necessitates grid-scale storage.
So vertical makes a lot of sense on large scale solar farms I think, even more so when you consider the land can be better utilised.
On domestic scale, where you can easier shift your load to match your production AND you might already have a roof with the right front and pitch, normal pitched north/south facing installations might make more sense.
This guy did some interesting real-world testing in a bunch of different circumstances - https://www.youtube.com/watch?v=5AVO1IyfA9M