I think Luna sounds fine but maybe some don't like her accent.
As for the rest of the characters, definitely enjoying them.
In regards to English vs Japanese in general, I've said this before but generally I like that English style voice overs are more subtle in the emotions.
In terms of games with just lots and lots of dialogue, I prefer that. Plus, it's more realistic.
Haven't heard or seen the full game of FFXV yet but in other games (especially VN like type games or other JRPGs), there are times where I find the Japanese to be a bit dramatized.
Mandy Moore as Aerith/Rapunzel.
Mandy Moore's is the voice of Rapunzel and an example of a few well known actors that also have done some VA work for games. She only did Aerith in KH1 but that's just an example.
With Mandy Moore, her voice is subtle. There's not too much dramatization.
Final Fantasy Spirits Within is another example with subtle voice overs from VAs.
There are some sad scenes. When a person is sad or crying in real life and trying to talk at the same time, most of the time they talk normally in between crying. A good voice for sad moments can have subtleness.
A lot of real life emotions displayed through voice is basically subtleness.
Anyway, I think FFXV seems fine from the clips. I know people may not like the accents but in games with lots of dialogue, I prefer the style of English over the style of Japanese voice overs. In regular Japanese conversations, it's usually not similar to the style in anime or games.
In English, whether because people are used to it from shows or whatever, the voice overs are usually a bit more subtle.
Though for FFXV, I haven't seen much scenes yet in both English vs Japanese yet to be able to compare fairly yet. This post is mostly just a defense of English voice overs in general.
The styles of English voice overs compared to Japanese voice overs is usually vastly different. It'd be better to compare English voice overs to other types of English voice overs.
Anyway, just my commenting on the voice over discussion from last few pages.