I've been using ColdFusion Builder for a while and am a big fan. Here are my five favorite features in no particular order:
It provides great CF insight
The ColdFusion language insight is great but its a bit of a given that an Integrated Development Environment (IDE) would have this so lets move on.
It provides insight on code I write
To this which is cool. Builder parses the code I write and provides insight on it. So if I write a cfc called Book with 5 functions and then in a separate file use the new operator, Builder will show the cfc's I've written and after picking Book will then show the insight on the 5 functions I wrote. It also does all this for ORM entities and ORM functions. Also, Builder provides insight on the variables I am using on a page. Parsing them as added and then providing insight on them. These two feature not only save time but they also significantly cut down on typos. In these ways Builder feels like it is working for me.
It shows parsing errors
Parsing errors are annoying and generally a small typo here or a missed quote there. When they happen its a trip to the browser, an error screen and then back to the IDE. Not so with Builder which shows them right away. I also find it satisfying when the red X's go away. (On some early betas this was quite slow but its performance has increased greatly on the final version.)
Its shows my logs
Before Builder I almost never read log files for errors during development. It took too long to find them or there was/is that tool that kinda works in the Admin but it was a real pain. With Builder, configure the Tailview tab and logs show up. Even better when something is added to the logs there is an indication by the tab going bold. This is extremely useful during Flex or AJAX development but also good during regular old page refresh development.
It works with virtual hosts
I generally don't develop in the web root but in virtual hosts. Builder handles this really well and even with some complex set ups it has worked well.
I was one of the many developers bugging, pleading and jumping loudly up and down for Adobe to build an Eclipse based IDE so I'm very happy they did so. There are some areas I think could be improved for the next version such as an easier project and set up process and a better SQL editor. I look forward to seeing what they come up with next.