RE: By my estimation, Legends is one of the weakest Classicvanias. It's not trash, it's just bland. Which is odd, because it has some idea that it wants to be special with its female lead, excellent artwork, branching stage, Burning Mode (press A and B together once per stage), trap candles, fancy-looking bosses, etc. Really, this game suffered from execution, I think. The levels are too long and repetitive, by and large. They're not really "fun"...most of the time they feel like chores. (Even as hard as The Adventure was, the stages felt more imaginative and fun in their sense of progression). Ideas like the trap candles or magic system lack polish, coming off as more frustrating than interesting like they should be. The creative, one-of-a-kind Bloody Tears remix that appears only in this game in stage 1 is truly a highlight, though. I don't care much for the story at all...but it could be a good start to another bloodline like the Morris or Baldwin family or something.
To your point on minibosses--other Classicvanias have them at one time or another: Dracula's Curse, Rondo of Blood, The Adventure Rebirth (every stage) come to mind.
Anyway, I remember this is one of the first CV games I owned for myself--still have it. It's a better game when you isolate it from the others and think of it as a intro to Castlevania or bit-sized portable Castlevania; though, even then it has its shortcomings. Also, I remember this, Dracula X SNES (which I discovered late), The Adventure (also a late discovery) and Castlevania 64 reviving my interest in Castlevania in the late 90s and making me a true fan after having stopped at SCV-IV as a casual player/admirer of the series. Those are my thoughts on the matter at the moment.