Very difficult! Nice job!
It think starting right away with the moving saw blades and spikes might be a little too unforgiving tho. The first level felt a little front-loaded in terms of difficulty as the second half of it felt easier. Don't get me wrong, it was actually satisfying to master that first half of the level to the point were I was getting very consistent at it. It just felt weird having most of the challenge be on the first half :). Changing them around would probably require a checkpoint or something though.
On the graphics side, I would recommend trying to maintain a consistent pixel size and scale. Your sprites and backgrounds look nice on their own, but together they clash with their different styles.
Overall this is very good for a first game using the engine (even better if it's your first game overall). Keep it up!