Hopefully now you see some of the value of del.icio.us. You should also be aware of the following, which might be viewed as risks or limitations.

1. Everyone can see your bookmarks by default.
2. If you can't get to the internet, you can't access your links.
3. Spammers may try to exploit social bookmarking sites.
4. There's no "controlled vocabulary" for tags which could lead to confusion.

However, depending on your perspective, these may actually be strengths. Note that you can enable "private saving" in your account settings.