My gay family members now have full rights, can adopt and marry and have all the rights that come with it in every State. Happened in no small part due to Obama's insistence and the general trend of acceptance that occurred during his time in office. That is a worthwhile achievementObama is able to polish his (poop) of a record a bit because he is neither Hillary nor Trump. Considering the short attention span of those polled, before too long Obama will have been deemed to have achieved something worthwhile in the last eight years.
Got rid of the asinine "don't ask, don't tell" policies, a worthwhile achievement
Accepted global warming as real, which in 2017 shocks me to have to call a worthwhile achievement yet there it is (and it will be gone from our Gov on Friday as the orange clown thinks it all a Chinese hoax)
26 States and Washington DC now have rational policies around Marijuana, that is a worthwhile achievement
I am sure there is more but it's not the point really as no one who hates him will admit he did anything good and few that like him will admit he did anything bad. As for me I'd say he was rather mediocre but history will show him far better than many recent presidents and far better than the next two (trump and then Pence after the impeachment)