After loading up Dreambuilder and playing with it for a while, I'm begining to question how useful this could possibly be for builders. The UX of the inventory is a mixed bag, while item access is improved with buttons and categorization there are some truly confounding decisions... like making the category list longer than the size it can fit in, requiring the user to click buttons to scroll it back and forth. It's also notable that the creative inventory takes up less than half of the space alloted for the UI in the first place, the default inventory and hotbar widths don't line up properly, and the hotbar slots aren't even properly marked in the inventory (have fun counting those by hand).
But enough about that. This is intended as a tool for builders, so lets look at the real meat: the visuals. Dreambuilder takes the interesting stance of mixing numerous texture and model styles instead of offering a consistent look, ensuring that only a subset of its massive item list can actually be used in any given building. Moreover, even with the author's HDX texture pack (mentioned on this page) the problems persist! Even the natural materials that spawn in the world lack visual consistency, often changing both in artstyle and texture density.
And then there are the loading times, which are bad enough that the author decided to warn users about them in the description. With a modern gaming PC armed with a fast SSD, loading an empty world takes "only" 30 seconds.
In summary--this is a tool for artists with numerous conflicting visual styles, poorly-designed and inefficient UI, and godawful loading times, that also expects a high-spec machine to run. All of these factors are going to make the process of building slower and more difficult, and just for good measure the latter ones will also make the resulting builds harder for regular users to view! You're better off with pretty much anything else.