I beat 1 just now. In exactly 5 hours including Dark Realm and the Bishamon sword that trivializes the final boss.
Its a flawed gem. I didn't remember the open ending and I thought it had some more bosses and scenes. But the final area is basically one corridor with a few boss fights. Game is extremely short, I think without dicking around and trying these gauntlets you can easily beat it below 3 hours.
But I like the risk/reward here. If you play good, ie abuse Issen, you get far more upgrade points and your health is returned. This is why I ended up using the green weapon the most. Because it has AoE on Issen. I did a small bit of NG+ in Panda suit, exclusively fished for Issen and both parts of my weapon were level 2 before the swine boss.
Yeah so I hope 3 comes a bit sooner after 2, and the new game still has these mechanics. Perhaps even the static camera? Probably not but I noticed I really like it.