My god people are actually comparing Dreamweaver and Coda.
Dreamweaver should only be used by people who don't know how to write html/js/css. It writes awful and complex javascript, it's css output is incredibly inefficient and indecipherable, and it's html is, well it's html isn't bad, but it's hard to screw up html too badly. The app is bloated (as most adobe/ former macromedia apps are). Its WYSIWYG viewer is not all that accurate. I honestly can't imagine how much you'd have to pay me to switch to Dreamweaver as my primary development tool.
Coda is my primary code app, but it has it's problems. The code hinting isn't perfect, and for some reason it can't search within as3 files. I could go on, but suffice to say it's my first choice for php/html/js/css development, and I have licenses for Espresso, TextMate, Dreamwrecker, and a few other code apps too.
For what it's worth, my dev cycle is to work locally, using the publish function in Coda to constantly be FTPing the files up to a staging server (or a staging folder on the live server) and testing it in Chrome. I'm past the point of needing live local WYSIWYG testing, but the edit->upload->test->edit loop with Coda's publish and a quick command+R in Chrome takes less than 3 seconds, so it's close enough.
I also write Actionscript 3 in TextMate and UnityScript in MonoDevelop, but I love my Coda for web languages.
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What's the learning curve in terms of using the interface? Somewhat like DW or is it more intuitive? Could you describe it perhaps as a DW lite version or are we talking a completely different user experience?
Coda has about 12 buttons in it's interface, and that's really all it needs... does that help?