Friendly, in this case, is a relative term and should not be used. Sure GDI/GDI+ is "friendly" however the performance hit is rather "unfriendly" not to mention the lack of real support on Vista/7, GDI is dying, let it die in peace.
EDIT:
Forgot to mention "Lock-In".
GDI, while supported fairly well by Wine, is designed for and around windows, therefore limiting your target audience.