The inverted castle is fun, but it isn't that hard to me. Of course, right now I say that because I've played SOTN enough to know where to get most of the secret stuff (great weapons, etc.) but really, the only time I think SOTN can be tough is early on in a 99 luck game simply due to the terrible HP alucard has (2-3 hits = dead on most bosses early on). I can barely remember my first time through. But... when I replayed SOTN recently I realized just how many bosses you can beat simply by jamming down the attack key and spamming some holy water in their face. It's not a lot, but SOTN has some REALLY shitty bosses, like Medusa, the Hippogriff, and everyone's favorite Karasuman. Not to mention some of the instant win gear like Crissaegrim and Ring of Varda (doesn't always drop in games, but if it does in yours, just one will make you overpowered, 2 makes you a god - especially if you can farm them early without leveling up a lot). Oh, and guys like The Creature... the only bosses I can think of that are hard are Richter (if you go for the bad ending) and possibly the big egyptian-styled boss in the inverted catacombs. Well, ok, I've always had trouble with the first doppelganger, but that's just because whenever I play SOTN anymore it's a 99 luck playthrough, so I'm usually weak, and I'm not perfect at dodging his attacks with the crappy reach of early game weapons.