Good, but could be much more
First, you have a neat submission here, and I think you may be on the verge of unveiling a new form of game walkthroughs. The seamless transitions between each area made navigating pleasing to the eyes, and the music was nice too. Unfortunately, I definitely noticed room for improvement.
First, the scroll speed is far too slow. Try giving people the option to zoom in and out or hold shift to scroll faster.
Second (as mentioned by GunnerRecall below) add some sort of index. For example, a drop-down menu could open to list locations of different items and bosses, which could then be clicked on to zoom the user to that locale.
Third, it may be a good idea to mark which walls can be walked through or bombed, since that's a big deal in the original Metroid.
Finally, I found it odd that you added little circles around the map and didn't make them do anything. Maybe you could have them reveal tips or other information when they're clicked on.
Overall, I'd say you have a good base for something amazing here. Tweak some things, build on it, and see where it takes you.