DD did not take a pacifier until she was about 6 weeks old. It is reported on the new SIDS guidelines to use a paci and swaddle when the newborns sleep. I do use them, but only on a very limited basis, basically if and when DD would be really upset part of the 5 S's (refer to The Happiest Baby on the Block by Harvey Karp), is to use the paci. At 8 mos old she will use them only at night if she wakes up to help her go back to sleep. If I give one to her during the day she will spit it out and play with it. Personally, I will be ending the paci stage very soon to avoid any issues as shopaholic stated above.
IMO a lot just depends on the baby and if you feel it is necessary to use the paci or not.
I do recommend the book by Harvey Karp just a FYI. Best book and we followed it to a "T" and had a very happy newborn.