I only ever used to use DW. However, I now hand-code. The reasons being: tighter control, the overall feeling of knowing what's going on, faster development (yep, honest), and lower costs. However, as adept at XHTML/CSS that I am, I am no expert in the likes of PHP (sufficient, but not hardcore). This is where DW can be helpful for me.
For example, I needed to do a quick PHP log-in system for my development server. I purchased an extension for DW about a year ago. I fired DW up, spent a couple of hours sorting the log-in system out, and there you go. Very useful.
As far as using DW for visuals... no way. For me (and I've said this in other posts), it's way too slow (on a G4 700 iMac, not the fastest, but certainly not the slowest), and I'm not happy with the CSS features (found it quicker to hand-code CSS than wait for DW to get on with doing it).