I think it's a fine design. I'm not as hyped about it as I was about Fujitora's, though. A bit underwhelmed, honestly. Sucks because Oda had been knocking these designs out of the park lately.
EDIT: The actual introduction is great, though. I love how Oda made the plant ability look incredibly terrifying and sadistic.
It's a shame that the full body reveal has him with the sunglasses. I think Oda overuses sunglasses on his male character designs, and it makes Ryokugyu look less unique.