A few reasons I like them: 1. The goal is to come up with a workable solution - not to try to fold your brain inside out to optimize them like leetcode. They feel a little more "real-world" (though still firmly in the domain of programming puzzle) 2. There is a community that all solve them at once. At my company, we have a leaderboard and a Slack channel discussing them every day. And then there is the Reddit and everything else that makes it feel more "fun" 3. They are bound (only 1 problem a day). Some days are longer, but I don't get overwhelmed like I do with leetcode where you can lose hours just churning through problems.

IMO, they are a fun community programming puzzle tradition. I would still turn to leetcode for interview practice. But AoC is awesome for me when I don't want to grind leetcode for some interview I don't want right now.