Honestly the first one is definitely worth watching. I am not a fan of the anime or the manga, cuz I've never seen it or read it so I can't really compare. As a s stand alone movie though, the first one is worth watching. The second one however, I feel is just a need to give the viewers an ending.
'Cause you give me something / That makes me scared, alright / This could be nothing / But I'm willing to give it a try / Please give me something
'Cause someday I might call you from my heart