"Bath salts" are predominantly cathinone stimulants similar to amphetamines. They have the same risks and rewards as amphetamines except since they are sold as "bath salts" and not actual psychostimulants
it is impossible to how much and what exactly you are taking!
Mephedrone was banned in many jurisdictions so it's unlikely the "salts" contain that anymore. Instead they may be any of the following: 4-ethylmethcathinone, 4-methylethcathinone, 4-ethylethcathinone, 4-methylbuphedrone, 4-ethylbuphedrone, MDPV, pentylone, pentedrone, butylone, keto-MDMA, keto-MDEA, methiopropamine, pseudoephedrine, etc. plus cuts such as caffeine, lactose, salt, talcum powder, titania/magnesia, etc. or any other numbers of unlabeled and poorly researched compounds.
The effects of the family are pretty general stimulant ones - high blood pressure, euphoria, stimulation, restlessness, wakefulness, psychosis, vasoconstriction, etc.
Look on Erowid for more information.
In short: these are a last-resort substance and should be treated with extreme caution. They will produce psychological dependence and even psychosis if misused. Stick to caffeine pills or street amphetamines if you want a guaranteed experience...