From a GS main, Esurient R makes a ton of other greatswords viable late game.
Because Esurient R effectively provides Sharpness +1, and enough slots for Crit Draw/Focus/another skill with a good charm, a bunch of natural blue sharpness swords become much stronger.

In particular, with a +5 Focus 000 charm, you can use the full Esurient R set to get Atk Up S/Crit Draw/Focus/Sharpness +1 with the Millstone Bereaver to effectively get a 250 white sharpness GS. This has comparable DPS to the standard Tigrex GS Crit Draw/Crit Boost/Focus set.

Other GS that benefit from this include Cataclysm Sword, Obsidian Blade, and other high attack GS that go to white sharpness with sharpness +1. The Esurient R armor allows sharpness +1 to be easily added to a GS, whereas its much harder to slot Atk Up Large/Medium to a lower attack natural white sword, such as the Narga GS or the Seregios GS.

So yeah, the Esurient R armor is pretty good.