When I first found Digg it was something new and wonderful. There I could find a virtually endless list of new, interesting and fun things online. Later I found Reddit and it was even better. Generally whenever friends told me about some news or something interesting online I already knew via Reddit (and no, they weren't on Reddit or Digg).
The only problem was that I didn't like how much time I was spending on these sites. The main reason why this is a problem is because it seems to be of practically no use. I thought I might learn something, and I do, but it's far more efficient to research things on an as-needed basis. I expected that the list of stories I dugg would be a resource afterwards, but it wasn't. Later I thought that the links I saved on Reddit would be more useful because liking was separate from saving, but it wasn't. If I really want to save something, bookmarks (or what IE calls favorites) make the most sense. I also thought I might be helping spread awareness about important things, but I guess I wasn't really (with a few exceptions), and there are better ways to spread awareness.
With Reddit, I remember the claim that it would learn from my voting and customize itself for me. This was very intriguing, but it ended up being a joke or worse. For example, for a long time the "recommended" section had very many Ron Paul stories, even though I didn't show interest in them. Eventually I started downvoting and hiding them, and that didn't help; the "recommended" section was still full of them.
Perhaps the most important thing I was hoping for was social interaction which would lead somewhere. However, it didn't lead anywhere. The most I can really say is that I can recognize a few usernames. Yes, the sites have "friends" features, but at best the Digg one was just useful for following people who digg stories I find interesting. Nowadays I also see what are undoubtedly spambots befriending many people rapidly. Before making any conclusions on whether social interaction there leads anywhere I posted a question on Reddit: "Did you make any friends through Reddit?". The response was quite disappointing. Not only was it pretty clear that people don't make friends there, but also many seemed to mock the idea.
It seems that practically all I get out of Digg and Reddit is temporary enjoyment. However unlike many other enjoyable activities, I don't look at it fondly afterwards. It's not memorable and it's not something I'm proud of. It seems like I should maybe delete my accounts there, but I don't want to do that yet. I still want to see if I can change things to make them fit into my life in a more constructive way.