Drakengard 2 may not be as canonically relevant to the NieR series as Drakengard 1 however I think it is worth experiencing especially if you want more story for the characters from the first game, even if they may be flawed.
The gameplay has the same formula but is improved with far better control, more balanced difficulty and a party system which requires you to switch between members to do a different types of damage against enemies.
The soundtrack again is incredible (best version of Growing Wings??) I think the storytelling is a bit clearer and although it doesn't have the same impact of the first game, I think it's worth experiencing afterwards!