As a 10+ year reddit user who has switched 98% to Lemmy, only checking reddit on my computer every couple days: Lemmy is completely fine, and I have seamlessly transitioned from Reddit.
Its userbase is more technical than Reddit's, and there's not as much content. But it is a perfectly good Reddit alternative. I find it isn't as addictive as reddit, which is awesome. I just wish there were more educational communities akin to AskHistorians, AskScience, etc.