I don't think it's the best game in the series but it has some very definite upsides.
The weapon variety is much greater than DS1, which gives more flexibility when you want to add some flavor to your builds while still being relevant.
Bonfire ascetics giving you the ability to control your difficulty and respawn bosses is a nice touch.
While the bosses aren't great, it's the last souls game before the bosses got really game-y. Since Bloodborne, bosses MUST have multiple phases, typically getting stronger once they hit 50% HP.
The DLCs were actually very, very good except for Frigid Outskirts.