It didn't feel that short to me, my completion time was also 4 hours 30 mins.
So much crazy crap goes on, I can't blame it for being that long. It's a dense experience is the way I'd put it, apart from the first stage of the last boss fight I thought it was great start to finish.
I'd suggest playing on hard anyway, I didn't know whether to expect Bayonetta level of difficulty and went with normal. Turns out I didn't die in combat, only on some QTE's. I'd try to learn combos but the enemies were too squishy for them, so yeah - go with hard mode (you'll likely pick up the parry system quicker too).