Does anybody know what are the drawbacks of using a paper phenolic
> based pcb on a simple circuit design?
If you're talking about something like XXXP, no (for a simple, low density circuit).
The stuff tends to delaminate in time, has poor heat resistance, and tends to get brittle with age. Still, recall that there are many restored 1950s radios and tv set in which XXXP is still servicable.
On the other hand, unless you are working with huge quanities of simple circuits, why would you want to use XXXP today? Traditionally, XXXP is used in mass produced applications where the holes in it are more often punched than drilled. For small quantity applications, G10 or FR4 are much more easily and accurately drilled and shaped than are paper phenolic laminates, and the cost of materials in small quantities is very nearly the same.
Harry C.