Condom; How reliable is it?

Yes they are if you use them right. That means putting them on before any genital contact, putting them on right, not storing them incorrectly, using old ones, etc.
To increase their effectiveness, many condoms come with spermicidal jelly already on them. If yours do not have the spermicide, it is best to use add some.

i never experienced doing the deed with condom, for me birth control pills is still the best contraceptives for me... maybe its still reliable but still the pleasure wont be the same as compared to doing it without condom...