Positives: The support team is quick to respond to questions. There is a good instructional video on how editing works on the site. The Uploader allows multiple uploads. Email notification of comments say what the comment is- this is unlike youtube and some other sites which merely tell you that someone has left a comment and force you to login to the site.
The site has a very strong community and the developers are very involved. It seems like the developers watch many videos and engage with the community.


Minuses: Experimenting with different start points is difficult. This is something required for editing. There are slight delays when you try to move to a part of clip. The editor is not yet competitive with imovie or other desktop editors. This may be a high bar to set but until it’s met I don’t see a reason to switch. The site doesn’t let you email people directly. You can only send them a public comment.
I mentioned that you can put more than one clip at a time in the uploader. If you do this it wants to package them into one movie. If that is your workflow then it is good but it's not mine. I Jumpcut’s is very editing oriented. So if you are just looking to upload movies there a few extra steps.
The site shows a posting time for clips but this only reflects when it was last edited (even if only the description was changed). This can make understanding how well your videos are doing difficult.

Overall this is my favorite video site, primarily for the strong community and interested, accessible developers.