Probably quite a few, but I'm not aware of any major ones except with
respect to directional couplers. 

Support on directional couplers is weak, but will be improved. Specific
areas of problems are:
a) Only able to do vaccume lines - no multiple dielectrics or fixed Er > 1.
b) Can't plot fields on couplers.
c) Not all the data that could be printed is printed. 

Lack of consistancy on interface of some programmes like rect_in_rect,
sym_strip, etc. 

Lack of any way of changing brightness of images without a
cpu-intenesive re-run. 
