It might not be too hard "after you git gud and learn how to use your sp", but for the starting area it's real rough. Like i said, it doesn't feel like an inferno or nightmare difficulty, just "hard".
No gun, no sword, slide only, and you're still getting used to the controls and movement, big open area, with zelda bushes that don't break until you find a sword but look like you could slide to break them if that's an attack, but nope, floating urchin is a dick, but ignorable mostly, kindof a bad trap at first, but whatever. Bat enemy is perfectly fine, but again, you can only slide, so you're likely to at least go for a few in the way, which eats more sp after you might've wasted a few on those bushes before. You'd assume you cna fill up on a save point, but lol, idiot you just saved with half your SP, and when you load, you're gonna have half your sp, good job!
Restart.
Maybe we'll go explore some around. Take a hit, do a little swimming out to explore, oh shit that eats SP too, hey there's an island with an obvious campfire, lets pitstop here. how do i start this? you can't. WAIT oops, gamer instincts kicked in, and you saved out here, congrats, you lost SP to get here and lose more to leave.
Restart.
Get to the first bandit. Man, he takes quite a few hits, and he's pretty fast for enemy #2, where the fuck is a sword, the practice room gave me a sword and a gun. Well, my sp is in the toilet, better just restart again.
Restart.
Fuck this bandit, i'mma just run past. skip room. skip room... dead end. where am i supposed to go? there's two doors, but no keys, it feels like LTTP or a mana game, so i guess one room needs to get cleared, so i'll go clear a room. OH, no drops, but now my sp is in the toilet again...
Restart.
How many times have i restarted now?
SP needs to regen to at least 50%, or get refilled by savepoints, i'd say both (for the fun factor). I don't recall running around using sp like was mentioned. Nah, this is not "ok". The attack combos and mobility is fun, and the sp hampering is like saying "I made this fun combat system, but don't have any fun with it." Give me more enemies or longer areas between save points, don't make playing the 'game' part of the H-game painful. Conservation-gameplay might be good for Resident Evil, but not for Secret of Mana. It feels like Megaman X, except i have a "dash gauge" that doesn't refill for an entire stage, except the bottom 2 energy dots, and i can't shoot when it's empty. Legacy of the wizard had your normal attack use MP, but in there enemies relatively constantly dropped refills, and even that game i never found fun unless i game genie'd that one thing off.
It's all just my opinion, but personally, with the SP hampering when everything uses it, i wouldn't even play this more than one or two areas if i got it for free, i'd get frustrated by that point and drop it, and lament it's space on my HDD.