Megaman zero HARD???? only thing i found hard was keeping a rank above C. Unless Zero 2 is hard I have no clue what you are talking about.
As its character designs I HATE zero he doesn't look a THING like zero and his gun its like a pistol. Where's his arm gun? If this didnt have megaman on it, it could pass of as another title.
Its called technology I guess. Its been a while since X.
And yes... the game was challenging. Its regarded as one of the most challenging games this generation.
The only thing I can complain about.... is how the game never tells you what happened to Zero for him to change so much. And considering Capcom never explained how Mega Man evolved to Mega Man X (not the character, but the series) I doubt we will ever know.
My personal theories regarding Rockman vs. X and Zero vs. GBA Zero:
First, I think the X series is more a retelling of the Rockman story than a sequel. Like Gundam X compared to Gundam - you have a lot of the same events and characters who went through a lot of the same things as in the original Gundam (such as the original pilot of the Gundam X, who was essentially a burnt-out version of Amuro), and of course a new rendition of the Gundam itself - but it's really its own show. I think Rockman X is like that. Dr. Light, Wily, Rock, they all show up in one form or another, even the original bosses (Cutsman->Boomer Kawanger, Ice Man -> Chill Penguin, etc.) could be said to have shown up early on in the series - but everything's given a new interpretation.
If you want to consider GBA Zero to be part of the continuity with the X series (which is tough in light of X7), my personal favorite theory is this: the beginning of Rockman Zero was meant to pick up from the end of X5, not X6. At the end of X5, Zero was blown in half and lost, presumed dead. Then at the start of Rockman Zero, the upper half of Zero is found, in some kind of suspended animation - he's reconstructed by the cyber-elf and given one of the handguns carried by the resistance fighters, hence the new look. I think it fits together really well that way - plus X had the Z saber at the end of X5 (which he did in X6, too - meaning that Zero had to have a different saber in that game). This is why I think the events of X5 were meant to be the lead-in to Rockman Zero. But then they made X6 (cheesy recycled crap that it is), Zero shows up and says "Oh, I didn't actually die that time.", and they had to come up with a new excuse to lead in to the GBA games - but meanwhile the original lead-in is still visible in the GBA game.
I do think GBA Zero was a cakewalk compared to the old X games... But it's a fantastic game. I think discarding some of the elements of the original games (like the 8-boss/8-weapon system, which never really fit Zero too well) was a great move.