I would say not necessarily.
But you have to use it right. Basically, don't either:
1. Do what I did in one of previous ROM hacks (levelengine knows the one) and have bosses that are more 'cheap' than truly difficult or interesting.
2. Make it pretty much do nothing at all. Bosses like that are 99.99% likely to suck, whether they use the n00b boss, newbie boss or custom programming.
If you need more detailed advice for it:
1. Do not EVER use homing projectiles with this thing. It does not limit the rate in which sprites are spawned, so anything that homes in Mario will end up becoming a nigh undodgeable zerg rush.
Oh forget it. Basically, if you make ANY boss, do not have it fire a barrage of homing projectiles. Especially not the homing Bullet Bills.
2. Don't use misleading hitboxes. It's 32 x 32 pixels. make sure the obvious target is 32 x 32 pixels.
3. Avoid the light flashing gimmick, because it's an absolutely godawful idea in general.
There's theoretically nothing wrong with using the sprite if its used well, it's just pretty much never used well.
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As for Mario's Nightmare Quest? Well, it's currently on Fusion Gameworks, ROM Hacking.net or the GCN at the moment.