Part Design Next allow using face as base for pocket. It's not ok for non-planar faces.
When I select a inner cylindrical face it results in a shift of the hole (as seen in attachment). For a double-curved the pocket is transversal...
I think face must be validate as planar before doing the function.
cf : issue #2823
OS: Debian GNU/Linux 9.0 (stretch)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.9896 (Git)
Build type: Unknown
Python version: 2.7.13
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17-dev