Discovered Webflow last week, it's pretty much perfect for what I need to do and already saves hours of time.
One feature I wish was available is the ability to edit/add CSS manually. There are tools such a CSS Hat that do a great job of generating CSS from photoshop layers, it would great if I could simply paste the CSS code in - or even type a quick line of CSS rather than having to navigate through the panels and find the control I'm looking for.
I've actually coded a Chrome extension which adds a Custom CSS pane to the Styles panel, it allows the adding of CSS to elements but is unable to retrieve existing CSS styles - it works well though for most rules.
Then I realised this could be a great opportunity for Webflow - if you exposed some of your JS API publicly, it would mean developers could create custom extensions to enhance and improve the capabilities of Webflow. For example, perhaps an extension that generates or integrates with a Wordpress theme.
Anyway, I have the CSS Chrome extension here if anyone wants to look at it - it's not perfect, but manages to handle most compatible rules without any issues.