I don't have twins but from what I've learned in breastfeeding classes and from doctors and nurses is that a mother's milk is the best milk for any type of baby or babies. Our bodies were made to give proper nutrition to our babies, so my advice is, if you feel like breastfeeding is the best thing to do for your twins, then do it and don't let anyone tell you not to.
Try checking out the breastfeeding forum :-) You might get a few more responses on there. Congrats on your two new ones! I'm a ftm so don't have much advice other than to trust your mommy instincts! If you want to breastfeed don't let anyone tell you that you can't because the body was made to nourish babies that way.