When is kapton tape useful as a bed adhesive?
I tested Kapton tape for PLA, ABS, PETG and XT. I know it works for other materials as well. What you need to keep in mind is that many materials only stick to Kapton tape well if you use a heated bed. 

The advantage of Kapton tape in comparison to other materials is its heat endurance and mechanical stability. It protects the glass underneath, while you remove the print from the surface. Some filaments stick so well to glass that you may break chunks out of it.  

The major disadvantage of Kapton tape is the time to apply the tape to the print surface and its very smooth surface pattern which seems odd in comparison to the rest of the print.