Safari 4 Develop
I recently downloaded and installed Safari 4 on my MacBook Pro and my initial reaction to the software is awesome! Today, I enabled the Develop part of the program and started playing with it while working on a web project. After troubleshooting a few css issues on a website using the development tools on Safari, I must say I am very impressed!
I especially like the resources view that allows me to look at what elements of my sites are taking the longest to load. Prior to using Safari 4, I was a frequent user of the Firebug toolbar for Firefox. Safari 4, in my opinion is much better for usability and is more aesthetically pleasing.
This impression may change in the future, but so far I am very pleased with the flexibility, the ease of use, and the design of the Develop functions of Safari 4!