Theres no side-by-side of the PDF and latex. Switching to the PDF viewer (and finding where you were, and finding the right zoom) is very clumsy.
One place Texpad is better is supporting multi-file documents well. In TeX Writer, I must navigate (manually) to the "root" document to be able to build successfully. The outline on the left sidebar doesnt see inside "input"s of other sections.
If I (again, manually) open one of the sub-documents, then I cant build. I cant even open the previously built PDF directly from that sub-document, because it isnt associated.
Also, I really like the shortcut buttons along the bottom of the screen. Its useful, but the command-autocomplete that Texpad supports may be useful in combination with these point-and-press buttons.
On the plus side, the dictionary and package auto installation worked smoothly, and the first document I tested did build successfully.