Shisui aint half bad, thanks to irremovable ignition... however in current meta, he is not that amazing anymore either...

1st: His scalling comes from chases and SOSP users almost always chose "dodge chases" passive.
2nd: He scales ninjutsu and initiative (well, ini scale is nice but only if there is a small ini gap...) where Obito 10t shuts ninjutsu users with seal..
3rd: He lacks any sort of leech / heal (when he remains last man standing).

his debuff reflect however works miracles.