The original Sicario was absolutely awesome and riveting. The action and sequences were both believable and breathtaking.
The Day of the Soldado was slow, political, very predictable.
It was a basic "hollywood cookie-cutter" action movie.
You'll find yourself saying... saw that teen girl with attitude in the Last Boy scout.... government betrays the agent like in 24... hero saves the little girl and then gets shot and lives...no surprise there!
I suggest watch and love the first Sicario and treat the Day of the Soldado as just a stepping stone to a (hopefully) much better 3rd Sicario.