Only if you don't have a slot-2.
Get an EZ Flash 3 in 1 if you have a DS Lite, or a full GBA flashcart if you don't mind the protrusion or if you have a phat.
Otherwise (if you have a DSi/XL), getting the SCDS2 would be worth it for the GBA compatibility if you LIKE playing GBA games.
If you...