In one way, Reddit is the best site on the Internet. Practically any new an newly discovered interesting thing shows up there. It often shows up earlier than on other sites like Digg or in the news. Generally, if someone tells me about something, it's already on Reddit. Sometimes I've already seen it on Reddit.
In another way, Reddit is the worst site on the Internet, because it is horribly addictive. It is the most addictive thing I've discovered, and I don't mean just on the Internet. It's also for the most part useless. I used to think that learning about new things there could be helpful, but it's far more efficient to actively seek knowledge which is currently useful. For example, I saved many stories from Reddit thinking some of that would be interesting or useful later, but it never was.
Reddit also has another downside: alarmism. That is stupid because it is an unproductive fad which is disconnected from real risks. For example, high oil prices led to countless Peak Oil posts and then, when oil prices went down, suddenly it seems like everyone forgot about it. Recently, there has also been some alarmism about the Swine Flu. There are also regular "outrage posts" about various injustices suffered by individuals. In all these respects, Reddit seems worse than the mainstream media. It's interesting how something like this happens automatically. I guess the upvote/downvote paradigm is simillar to TV ratings, but there's probably more to it than that. I guess Reddit is getting better however.
Despite the downsides, I like Reddit. I think the main strength of the site is the sense of community which sometimes exists. Discussion of new and interesting things is not innovative. It's an old idea which has been around for a long time. It also has no staying power; it draws people as long as Reddit presents new and interesting things, and if another better source appeared, those people would move on. However, what goes on in some "self" posts and the occasional deeper thread of comments is different. There, I see signs of a Reddit community. That makes me think that Reddit might even be immune to the sort of decline that Digg experienced.