Music? Different people have different taste so I can't dispute this but I can't remember a single track from SotN while the
village and
pinnacle themes from DoS are still stuck in my head. Same with
Iron Blue Intention and
Crucifix held close from PoR and I usually don't pay that much attention to music.
Transformations? Uppercut all day everyday, transformations just slow you down. And turning into giant monsters in Aria >>>>>>>> turning into mist. EDIT: Just remembered the wolf one. That was nice.
Controls? I'm not sure how SotN is better in this regard. Can't remember any control issues in any of the IGAvanias.
Weapons? It does have Valmanway but so do the Sorrow games. Does SotN have Claim Solais, Balmung or something similar? I'm seriously asking because I didn't mess around with it enough to find all the weapons.
Unnecessary? More like fun and another reason to make killing enemies more enjoyable. Dawn takes it even a step further by using souls to synthesise new weapons, a mechanic that's sadly absent from the sequels. Alucard's arsenal is WAAAAAAAAAAAAAAAAAAAAAAAY more limited and certainly not good enough.
More secrets? Can you jog my memmory? All I remember are breakable walls.