No. He wasn't self-revelatory in the beginning, but that doesn't mean that the traits he displayed couldn't be seen in a different light if given more thought than relying on surface impressions. Well, at least, one doesn't see the incessant Jar Jar Binks crap, at least not here any more.
I think that his behavior was always led by the same drivers, although we didn't know about most of his backstory and the meanings behind his motivations for quite a while. Still, I think that the behavior we saw in the first year or so makes sense, even with our limited knowledge. Why the brashness and braggadocio when he found that he had serendipitously scored a jackpot by coming across Voyager? Well, in some part, I think one can relate that to the relative lack of social interaction that had been his lot for a while and also just not realizing the wisdom of curbing his exuberance given the structure and organization of where he found himself. Beyond that, I think it's plausible to consider that having had to live alone, relying on his wits, he might very well feel that being on such an advanced vessel with aliens that seemed friendly enough, he still had to be wary and projecting a vociferous, argumentative, and apparently self-confident persona would protect him from being perceived as weak and replete with vulnerabilities.
In a similar way, the extreme possessiveness of Kes during the first season and in snippets afterwards can be seen in the light of what is apparent from Caretaker, that he is cognizant of the rare and extraordinary character that is ineluctably apparent, if for no other reason that she has done what few if any other Ocampans had the determination or interest to do, escape from their comfortable tomb. Even without any intimation of the psionic powers Kes would come to display, Neelix instinctively understood what a precious and, from his perspective, undeserved gift that their relationship had bestowed on him. On Voyager, I believe that he endeavored to take as prime and integral a role in shipboard life as he did, not just to justify his value to the crew, but while unstated perhaps, to Kes as well. But being in the midst of a large number of men, some of whom would also be inevitably attracted to her, Neelix was unable to discern that her unquestioning devotion for him far outweighed, in fact negated, his persistent self-doubts, and felt compelled to fight the non-existent threats by trying to ever tighten their connection by convincing her that only he had her best interests at heart, and that the attention of others, Paris especially, were self-serving and exploitative.
Neelix certainly did grow in the surety of his essential goodness, wisdom, and caring nature, a process that started before the rupture with Kes (Jetrel), but definitely became more apparent afterwards, as more attention could be given to him solely, not focused on the dynamics of a relationship that was destined to end sooner or later.
So, in the sense that I think the OP is intended to mean i.e does Neelix become more tolerable and perhaps substantial, I again would reply in the negative. I think, whether purposefully or not, the writers created a character whose actions, demeanor, and integrity were always present if one gave the time and consideration to look for them. As the Doctor once said, it's like peeling an onion.
He likes Trek in a casual way. He won't watch his favorite episodes over and over again like I do.
It looks like I might have been worrying for nothing.
And he seemed pretty much a loner except for Wixiban.
