critical effect/damage + crap about warlocksFollow

what % is it to do a critical effect/damage/strike?
+ is what i've heard is true? warlock sucks on a high level cos i doubt this in a way.... cos i figgered out that warlock can have a 15% chance with searing pain, yes i know weak, but faster. but with ruin a CS is equal to do a shadow bolt but critical strike every 1.5 secs and 10% to daze for 5sec, which is way worth it! anyway, i could go on about it forever saying all the pros and cons and etc. But if the chance it already highish then shadow bolt mite be better.(+ im not a newb, played the wow beta, for a week. SHUT UP those who dare mock me!)