The USPTO’s most recently published IPR statistics show that the odds still greatly favor the patent challenger:

Given that a settlement (presumably), a request for adverse judgment, and a finding of patentability are all good outcomes for the patent challenger, patent challengers have “won” 58.4% of the time, and when you add in invalidation at least some of the time, then the patent challenger improves its situation 63.9% of the time.

The odds are even better for petitioners who do their homework and present a grantable petition.  For petitions for which trial is instituted, the challengers win 77.8% of the time, and at least improve their situation 86.4% of the time.