Its a good learning aoftwae specially made for student who study networking and need a simulator for their studies.
Packet tracer has been a great tool to confirm the practical aspect of the networking theory. I personally recommend this software for the students who are prearranging for cisco certification.
There is another softwares like GNS3 which have more features than packet traver but it is good and basic for associate level ciaco certofication. But if anyone is going for ccnp or other professional level certification in networking he/she should go for gns3.