I like the option to swap between a light and dark theme. I feel like the light theme is a bit too light, though. I've been using the dark theme and highly prefer it. It's just dark enough not to strain the eyes, but keep from being a 2010's dark black theme. I think that should be the default. Your sidebar keeps quick links handy, but I'm not sure how it pairs with the top news bar. You already have a News link on the sidebar.
The largest turnoff is the unfortunate byproduct of posting packages or quick posting. There are a lot of generic threads with no replies. There isn't a sense of engagement. It can come off as a bit daunting to new members who would come to help build the forum, scrolling through a graveyard-esque wall of threads. There aren't many remedies for this other than to find ways to get members to register and start replying. I would suggest laying off the quick posting for awhile, as many of these threads are all created within an hour of each other.