There are some small flaws here. The biggest (and certainly not your fault) is that the collision detection on spikes in sideview gravity can be a pain sometimes. Then there are little hiccups like trying to line Link up on a vertical ladder through a narrow gap and the brief but risky delay between the time you shoot, and the time you are allowed to jump. On another note, the disappearing blocks take too much time to reappear.
Some players may be a little frustrated about the one arrow on the screen limitation, and the fact that powerups are a little bit scarce (it's can be hard to refill after a boss) but I never found it too frustrating. Only one or two bosses really were bothersome (such as Whizz Man and another boss or two that slips my mind). I found the difficulty manageable and only had to redo things a couple times on occasion.
For the most part I stuck to the arrow and feather, I didn't learn the weaknesses (assuming you put weaknesses in there).
The graphics are the basic set, but really well chosen to look like Mega Man stages. A few more original graphics, and better palettes would've been nice, but as a Z1 style game, it works. I do have to point out that the small health and energy pellets are incorrect. The health should be round, not oval, and the energy pellets are larger than that. I don't know why you didn't rip the correct graphics for those.
I think this took me an hour (or an hour and a half) to beat.
I liked this quite a bit. I give it a 4
I myself altered some of the tiles for Link. 
