Short version: good, if somewhat obsoleted now. Long time ago was a top tier character. Read more below if you want a history lesson :)
When OPTC was starting, he was one of the best captains. Luffy was only bosting STR characters, Decisive Battle! Hawk Eyes Mihawk was not released/new&tough, and he was the second rainbow lead after Chef Zeff - and with much better stats. Together with tank Zoro, he was one of the two best early captains. As the game progressed, of course, he lost his captain's seat to Hawk Eyes Mihawk. He is also hurt by weak special and a single socket. Despite that, he is still useful as a STR Slasher sub due to his stats: as of late December 2016, he is still the second strongest STR character (by ATK value, superseded only by Tony Tony Chopper Post-Rampage - and still top for Sengoku). He is still the strongest STR slasher. If he has been obsoleted by anyone it is by himself: his FN Arlong Sun Pirates has 102 less ATK stat (still a reasonable 1389, 2nd highest STR slasher, Top 10 STR ATK characters), three sockets and a more interesting special.
Socketing guide: very tough choice given he has only one slot. Auto-heal will help with slasher teams aiming for max auto-heal and stalling strategy, or you can chose one of the other good sockets (Matching Orbs, Charge Specials, Anti-Lock, Anti-Despair).
This character may be needed for missions on his story island, but currently it is unknown when, if ever, such missions will be released.