Macaw is much closer to Fireworks than Photoshop. I've never used Fireworks but a colleague of mine did. It's so much better suited for web design. But Adobe failed to market it properly (I actually never heard of Fireworks before 2011, several years after I started). That's probably the reason why it's discontinued.
Macaw tries to capitalize on this void left by Fireworks, a void that actually may have never been filled by any web design software. I think the keyword is "fluid". Unlike Photoshop, almost nothing in Macaw is engraved in pixels. You can easily modify elements without worrying about half-eaten pixels, resizable boxes or weird rounded borders.
Sounds like Fireworks? Yes, but Macaw adds a powerful feature (and probably the most criticized one): code generation. As some others said, it does sound like Dreamweaver. But Macaw's code quality is vastly superior and quite impressive.
Being a front-end developer and a graphic designer, I'm right in Macaw's target market. I think I'll try it out but I probably won't use much of the generated code. I'm comfortable enough with CSS to understand how my own written code will behave in the browser. I've developed best practices that would be hard to merge with any software generated code.
But Macaw is also a design tool with interesting features. And having missed the Fireworks train, I think I'll try to catch this one. My design process have grown simpler and more focused over the years, and although I'm comfortable with Photoshop, it sometimes feels like an overkill.