I've talked to a few friends who have purchased the game, and one whom i actually bought the game for. It's such a great product. However, as much as everyone loves it, we've all come to the same consensus. We're older, don't have the time to invest in to being excellent with the mechanics, and actually love the atmosphere and story. We're the weird guys that didn't mind the excessive banter because it's just like the old anime we loved!
The lack of an option to just go through stage by stage is what's killer. It's like we're forced to play new game plus ALL THE TIME. You die, you start ALL the way over. As much as I love it, I look at the game on my PS4 queue and move on to something else. I finally made it to season 2-3, died, and was like, "what am I trying to prove again? I did all this crap with (insert hardcore game from 30 years ago).
This is actually much harder than Bloodborne or Dark Souls. When you die in those games, you loose a little progress, you've still got your weapons, you can heal up. There's reward of progress through attrition.
Galak-Z? Just CRUSHES you. You die, you start from SCRATCH. I had some frustrating times in Bloodborne, especially when that super long load screen was still in the game. However, I never felt that crushing despair. I always felt like I wasn't approaching from the right angle and would reassess my tools, or my weapon, or my patience. You were only a quick jaunt to the obstacle. You suffer a few times, then press onward.
Galak Z crushes you and when you are forced to start at the beginning every time, after while you're just resigned to play something else and pick it up later. Maybe.
Even in Rogue Legacy, NO run is in vain. You keep something, spend it on your upgrade tree, and you're ready to go again. It never feels like a waste of time or lack of progress.
EDIT - for those of you saying how easy the game is, I assume that all of my friends and i completely suck. It took me days to finally get to 2-1 (admittedly playing for only about 30 min each day). I just don't have the dexterity anymore. I liken it to when I was really into Street Fighter and moaned about the one-button easy controls for neophytes. Looking back, though, I don't care if that stuff is in the game as long as there's a separate way for me, the hardcore, to enjoy it, and a way for them to enjoy it, too.
If the game had a mode that allowed you to start each episode from scratch, even that wouldn't be terrible.