1. Its look. It looks very much like the face of an iPad, iPhone or iPod, but it is not affiliated with Apple (that I know of, anyway). I like the visual ease on the eyes.
2. The sharing aspect. You can search for webmixes in the Symbaloo gallery to gather resources that others have found ahead of you. Likewise, you can share your own webmixes via social sites like FaceBook and Twitter, in a website, email, or in the Symbaloo webmix gallery.
3. Simplicity. Ideas that come to mind for integrating this tool into your classrooms abound. Students could create their own collection of favorite bookmarks, research sites, useful classroom tools, etc.
I am currently creating webmixes for staff to use with their students in their classrooms. I'm also able to see what subject-specific webmixes already exist, and I encourage all educators to explore those webmixes that best fit their area of expertise. I actually think this may be a more efficient way to share free web resources than posting lists on this blog. That said, expect to see many more Symbaloo-related posts as the year progresses!
Here is my general EdTech Integration Tools Symbaloo Webmix. It's a perpetual work-in-progress, so stay tuned for additions as the year goes on, and check out Symbaloo for yourself. Just think of the ways you can use this with students!