I just ported a large iWeb site over to RapidWeaver. I am very happy with the end results, but some of the process drove me nuts. This isn't the RapidWeaver works differently than iWeb stuff, I can live with that and I understand many of the reasons. What bothered me was I often felt like was mousing all over the place. It felt likeI was playing ping pong, first going to the bottom of the interface, then up to the top, then... Case in point: links. To add a link you HAVE to go down to the bottom of the page to click the plus symbol to add a link. There is no menu option/keyboard shortcut for this, so you MUST head south. Then the link sheet comes sliding down from the top of the page and you must head all the way to the top of the page to press the popup menu in the sheet for link type.. No choice here either. On pages with lot of links, it felt like a game of ping pong. I ended up making a Quickeys macro to avoid mousing all over the place. At the least there should be an add link command in the menus and it should have a keyboard shortcut to use as well. In an ideal world this command should appear in the contextual menu you get when you right (control) click. This way you select the link, right click and call up add link right from where you highlighted the text.
I also woud like to see some work done on the HTML commands. Their behavior is somewhat inconsistent. If you are working in the main window there is a popup menu at the bottom for HTML. If you are working in the sidebar their is no such menu, you must go to the top of the screen to the edit menu. Why this difference? Yes their is less room at the bottom of the sidebar dialogue box, but use small icons like the Stacks plug-in does under their main window. The same is true for the rest of the text formatting controls for the sidebar. Or just use one set of formatting controls that applies no matter where you are working. The HTML controls should have keyboard shortcuts assigned to them. Once again in an ideal world the HTML controls as well as the text formatting controls should appear in the contextual menu too.
The built in Photo Page should have better support for captioning. As others have suggested you should allow more meta data in. Perhaps their should be a preference tab with selections for which metadata to bring in. I had captions in Aperture which I couldn't use. When you go to use the captions field you are limited to a long narrow single line input area. Why not have an optional button to popup a small dialogue box which will show multiple lines of text allowing you to view the whole caption at once. Right now editing captions is painful.
I'm sure you've heard this many times before, but you should be able to see both the Body and the Summary version of the blog in the Preview Mode right in RapidWeaver. You shouldn't have to publish just to see both versions, or avoid using the Summary until the very end so you can see a preview of the Body. I could see this being a bug, but not the normal behavior.
Don't get me wrong, after 5 years of using iWeb, I am now a huge fan of RapidWeaver. I am very pleased with the site it allowed me to create. But there were times I wanted to bang my head against the wall.