You Don't Know Beans
Unless you've checked out the latest NetBeans 4.0 RC1 release, you really don't know beans about NetBeans. If you've been using the 3.x line of NetBeans for a while, this new version may be somewhat challenging at first.
The entire project configuration is built around ANT. The move to ANT might be confusing at first. Of course, there are ways to import existing projects that do not have an ANT configuration. However, I think it's safe to say that this version definitely prefers to work with ANT targets and tasks. For example, I found it hard to even debug my "freeform" imported project without creating a new ANT target for that purpose. The wholesale dependency on ANT targets feels a bit tedious at first, but I have a feeling it's going to help me manage projects better.
Remember all those "mounted file systems" in version 3.6? Gone. Multiple source directories? Apparently gone for default new projects. Help me out here if they really are still available.
I know there are lots of other popular, useful, and powerful IDEs, and you may not want to consider another one at this point. However, if you are still undecided, or if you haven't checked out NetBeans in a while, you have to see the latest NetBeans offering. You'll definitely find something in there that you like.