I was hit in the Norfair wanna-be area, along the left half of the area somewhere, though I suppose the problem relates to if every warp trigger is coded separately (which I have seen people do) or if you made a 'jack of all trades' function and treat the warp areas as objects (which is what I do).  I think it was down to the exact frame where I was hit as I was being warped to the next room, so I would call it a rare bug, but one that happened to hit me (pardon the pun).

I got to the "To be continued" screen, yes.  I remember seeing that room with the tall thing and the four different coloured blocks that resembled your key system setup, so it was not hard to figure out.  I was a bit surprised to see a lack of final boss, given all things.  

I started around 11pm or so and finished around 1:30am, though I had a 15-minute break during that, so... 2 hrs, 15 minutes, which is about as long as some of my longer games.  I did die a lot while I played this. On another note, this is the first game I have actually played in a long while.

The biggest complaint?  Well...

• A lack of save game capability and I am inclined to agree.  The unlimited lives concept helps, but there is no way to resume the game if you have to stop for a while, something that could be a bigger issue if you plan to port this to consoles with a limited battery life capability. 
• There is a lot of horizontal backtracking that happens throughout the game, so much I would nominate you for the "Magmoor Caverns" award.  What might help to mitigate it is some sort of unique transport system that could take you back and forth between the left and right sides of the game?   I would not worry much about the vertical stuff, but having to solve the same puzzles in the same rooms over and over again starts to feel a bit tedious after an hour+ of gameplay, especially when they offer nothing new along the way.
•  I had a heck of a time timing my double-jumps; this caused a number of in-game deaths.  Maybe it has to do with how fast the jumps are? I guess I am just used to coding in slower jumps and handling the multi-jumps on those...
• You mention a 'level 1' weapon, which implies there could have been upgrades to your weapon system... Of course there are none, so that was a heck of a tease. :P

As for the good?  Well...

• Your map concept is fine, I would leave that untouched.  The whole concept of new rooms is not a bad idea, because it gives a sense of direction and 'where to go' as you play, which is a nice touch.  
• The background ambience...  I admit it is odd, but I would leave it; it seems to work for this sort of game (which sounds very familiar; I place a music track for a game area which I don't think works, but I find it grows on me as time passes, so I leave it there).
• The bosses work well and I would stick with them.
• I liked the idea of hidden messages scattered through the game.  I am not actually sure how that contributed to the storyline (to be honest), but there is nothing wrong with adding in a little in-universe lore, especially when you go to such trouble to draft such ideas in the first place.

Overall?  You did a heck of a solid job. Your dedication and effort reminds me of what I go through to make my own games.