Firstly I would like to say that the Unified Transform tool is a brilliant idea - much easier to use than a combination of the separate tools and only one round of interpolation at the end.

There is, however, a problem if you are using the tool on a reasonable sized image and want to zoom in to fine tune the transformation - the control points disappear and the only available operations are moving the whole image or moving the centre of rotation (unless I am missing some way of selecting the other operations).

With the individual tools (rotate, perspective, shear etc.) it is still possible to make the transformation even when zoomed in.

One possible solution would be use "View/New View". the additional view that results can be zoomed independently to the main/original view and can be used as a magnifier for part of the image. However, for this to be a solution the additional view would need (possibly as an option) the ability to reflect the state of the main view in real time - currently it is only updated on the completion of an operation - for example a line drawn with the pencil only appears in the additional view when the mouse button is released, whereas the part drawn line appears immediately on the main view. Similarly the effects of the Unified Transform tool only appear when the operation is completed.

Adding this real time updating of the New View would also provide something that would satisfy Enhancement Proposal: Add a temporary magnifier http://www.gimpusers.com/forums/gimp-developer/5849-enhancement-proposal-add-a-temporary-magnifier#message26965

A second solution would be to always display the control points of the Unified Transform tool no matter how far in the image was zoomed but this solution (if possible) would have a less broad application than adding the live view (option) to the New View.

Is there a good reason why the extra view(s) initiated by "View New View" only update on the completion of an operation? From my point of view it would be better if they reflected the active view (or a sub-set or super-set of the it) complete with any on-screen preview or partially completed drawing operation etc.