It's all a case of personal preference.
- Some dislike DW because they simply like free products and dislike Adobe more so than DW.
- Some dislike it because they think it's a kids toy, and would prefer to use much more "kewl" editors such as aptana. apparently it "proves" how proficient they are as a developer...
- some dislike it because they have tall poppy syndrome.
- Most however dislike the design view component of DW. and for good reason - it's truly horrific...
Having said that I use it every day and thoroughly enjoy it. I never use design view and can manage all I need from it so have no desire to use anything else.
you can try and use notepad++, aptana, coda, etc etc, but in the end it still comes down to personal preference.
If I dealt with truly hardcore programming languages on a daily basis perhaps I'd need something more substantial but for html/css/js/php editing it is more than adequate.