serial link speed question
I am studying for the ccent 100-105 and have a question regarding speeds of links. I am confused that it is written in my book that the speed of a serial link is 1544 kbps or 1.544 Mbps. Isn't this too slow, since right now I can speed test my laptop and 3.0 Mpbs download speed. Are serial links something that is not used anymore (some of the cisco topics seem that way)? Thanks very much for all the help.