How good is the pull out method?

It isn't: It is not a dependable approach. If you don't want to get pregnant, you need a better method such as condoms or bcp's.

Too risky: No studies for definitive stats,...To get pregnant sperm needs to enter the vagina during or around the time of ovulation. At times, there is the rare chance that "pre ejaculate" or "pre-cum as a slang" has some sperm cells in it, so please do not rely on the Pull-out method for Birth Control! Use BC pills and condoms as well to prevent both Pregnancy and STI's.