some of the fine print:
only timely payments in a qualifiying repayment plan count towards the 120 required for forgiveness, standard, income-contingent, and income-based. payment schedules like extended or graduated do not count towards the total. the standard repayment is amortized over 10 years so 120 payments would leave you with exactly zero to be forgiven 10 years down the road.
income-based and income-contingent monthly payments are calculated as a percentage of discretionary income above poverty level for family size and how much you borrowed. in reality a married couple who both work with one or two kids is not poor, so very little reduction in payment occurs. once the employed is making the equivalent of approximately gs-07 salary you will be moved to the standard payment plan for the remainder of your 120 payments.
there are obvious ways to game the system, single parent 3 kids perpetually employed at gs-05 will have more forgiven after 10 years than a single individual in an upwardly mobile career ladder position. but there are probably not very many college grads with student loan debt whose resume reads stagnant government clerk and ghetto mammy. most who qualify for the program will only have 2-4 years at reduced monthly loan payments before paying the standard plan full frieght.
rough calculation is $40k debt at lowered payment for a few years gets $8-10k forgiven after 10 years. less than $1k/year or $100/month. given the lack of cola's, reduced benefits package for new hires, increasing workload as vera's and hiring freezes work their magic, not to mention public perception of gov employees, and loan forgiveness seems not to be as big an incentive as promoted. there may be other rewarding careers that pay in excess of $100/month vs. gov that one could pursue and be financially better of not qualifying for loan forgiveness.
biggest caveat of all: student loan forgiveness is a 'play now pay later' promise cooked up by politicians and as such is subject to change, most likely at about year 9-1/2. ask detroit how that is working out for them.