Alright, it's honest review time from scarfu over here. =w=;; If I say anything that offends you or anything, I definitely do NOT mean it in a hurtful way -- I'm just stating my opinion. =w=b
Starting with her voice, I'd like to state that I /adore/ it. It's very cute, and very perky, and it's full of bubbly personality, which I really, really like. It's also very clear, so overall you did a very good job with it I think. ^u^
However, my critique lies mostly within her design, where I personally think needs... a little work. ^u^;;; This is only an opinion mind you, she's very cute as she is! But there are a few points I think should be taken a look at...
Her color scheme is very, very cute by it's self -- the colors all work very well together. However, I think your choice of... accessories and overall setup of the outfit really is pushing the Crypton look a little too far... I mean, I won't lie, I incorperated the loop belt things onto my own UTAU as well, but Luna's design just feels... like it lacks a lot of originality that I'm entirely sure you could put into it. Like... I think rather than designing her to be a wannabe Crytponloid, you really should focus on developing her as an UTAU because... well, that's what she is! XD I... think it's part of her personality that she wants to be a Cryptonloid, so I understand why you would take that approach, but I also think that this is a bit of a problem -- having Luna's existence revolve so heavily around the Cryptonloids, Len in particular, gives off a very... negative vibe to a lot of people who first stumble upon her. The... uncut version of what she appears to most is... well, a mary-sue self-insert Vocaloid OC who was given life by UTAU. XD;; That was what I thought of her before I had gotten into this fandom anyway, when I was just looking at the wiki page and eyeing everybody who was there.
Now I really don't know too much about Luna other than what I've read on her wiki and what I've heard around, so my opinion is probably ENTIRELY unfair. XD; But I just think that you should keep in mind that those are the kind of vibes she's been giving off... at least to me orz.
Overall, I think Luna is a very cute character with a GREAT voice, just her design and character overall needs a bit more work to fully pop out, and I am ENTIRELY sure you are capable of doing it. ;u; <333