No idea if anyone is still reading this, or if the list of people who might still be reading this in any way overlaps with the list of people who care about Veronica Mars...but one thing I've realized about myself is that I have a compulsive need to talk through my ideas, and an audience is nice, but not 100% necessary. So here goes (with spoilers, of course).
1) I thought they did a really good job letting Logan grow up. When I heard that the central premise was him being accused of murder (again) because his girlfriend had been found dead (again) I thought it was a pretty discouraging sign. If Logan ten years later is the same directionless kid, hanging out with the Casablancases of the world because they won't ask him any hard questions...that kind of cuts into his attractiveness. On the other hand though, if they gave him a happy life with a serious girlfriend and then killed her off, I'm pretty sure the only realistic way to portray the aftermath would be a padded room, or Veronica trying to clear his name after he committed suicide. Either way, no looking forward to the romantic chemistry between him and Veronica. But the relationship they gave him to Carrie Bishop made sense to me, as did the idea that his involvement in previous murders would make him especially vulnerable to being framed. I also think the military is a pretty perfect fit for him. In Seasons Two and Three, it's really striking how very very alone he is...I get mad at Keith for throwing him out of his house when he fights with Veronica, not so much because that's not the right way to react to someone losing their temper at his daughter, but because I feel like an adult man should realize that what Logan needs is not to be thrown out but to be taken in, and that if he doesn't want that burden falling on Veronica maybe there's a role for him there. I don't honestly know much about life inside the Armed Forces, but I hear that the sense of belonging is one of the real positives. Logan is obviously intelligent, but he's more motivated by bravery. It seemed obvious as soon as they showed him in the uniform. So good job there.
2) Grown up Veronica made slightly less sense to me. I think they probably could have fleshed this out better with more time...it's bizarre how short a movie seems after a TV season. The closest they got was the conversations between her and her dad about success and respect, but I wish they could have fit in a conversation with Piz about their future plans too. I actually liked grown-up Piz, and after rewatching the third season have more of an appreciation of how his character is meant to be conscientious and idealistic in a less embattled way than Veronica herself. I didn't like the premise they used to break her and him up, it felt artificial...but also like there was also just a lot of detail left out. (They apparently broke up for a while and then got back together? They're serious but she hasn't met his parents? He's got a hipster dream job and she's going for corporate sellout?)
3) Speaking of the breakup...one of the real strengths of the series to me is the way that friendships intermingle and get even footing with romantic relationships. Logan maintains his feelings for Lilly while falling in love with Veronica, they both still manage to care about Duncan while falling for each other, Duncan and Veronica have obligations to Logan as his friends even though she's broken up with him and he's stolen his exgirlfriend, and then the same dynamic plays out with Meg, Jackie struggles to understand why Wallace is so committed to a friend instead of "the girl he makes out with", Parker worries about dating Logan without endangering her nascent friendship with Veronica, and Wallace and Weevil both have their issues with Logan that are much more motivated by friendship than jealousy. And then Piz breaks up with Veronica because he can't understand why she's prioritizing keeping Logan out of prison over meeting his parents. Without more context on their relationship it's hard to say for sure, but it's hard to picture Veronica in a serious relationship with someone who gets threatened when his girlfriend cares too much about her male friends. Sure, Logan is not just a friend but an epic love...but she hadn't seen him in nine years, since freshman year of college. (Also, Eli had just gotten shot the day before...is that not a reasonable reason to stay an extra day?)
4) And Eli. It really bugs me in Season Three how Eli is supposedly trying to get his life on track, and Veronica keeps asking him to steal one more car or commit some other crime for completely petty reasons. Sure, if he gets caught, his life is pretty much over...but Madison St. Clair is such a bitch! It seemed unrealistic; oblivious to the rest of the way Eli's character is written as an insightful human being who sees the trade offs and compromises of his environment. I feel the same way about the writers putting him back on a motorcycle at the end of the movie. I get that they're putting everyone back in Neptune and in a facsimile of their original role for possible sequels...but Eli deserves to grow up at least as much as Logan does, and not just be a plot device for when Veronica needs some crime done. (Wallace completely refusing to steal a school file though? That was pretty awesome.)
5) I have similar feelings about the fight at the reunion. I can see why the writers wanted it...it makes a great clip for the trailer, it's one of the few moments of character development that Piz gets, and it provides some nostalgia for fans. But I think it kind of undermined Logan's character development. He's handling being accused of his ex-girlfriend's murder with restraint and maturity, doesn't make stupid decisions to get in trouble anymore, but starts throwing punches at the sight of Veronica's ancient history sex tape? Who did he even find to punch? Not Madison obviously. I think I would have liked the scene better if they had let Piz throw the first punch...or if that's too out of character, maybe Wallace or even Dick. Eli's wife? Pretty much anyone. As is, it comes across as a mindless replay of the TV series' greatest hits. (Same with Veronica and Logan's big kiss. I'm not sure what else they could have done, but I'm pretty sure the scene would have had more impact if it had been less like their first big kiss).