I like http://www.getpaint.net/index.html, doesn't consume as much resources as photoshop (i presume) but it is easier to understand.

About your picture, what i dont like is that there is almost no contrast between colors. An example of what i consider an improvement:

Also you use a lot of colors, try to reuse your colors next time. You seem to know how to draw, so it wont take you too much time to learn this concepts, not like me.

I've been using this since it's easier and less computer intensive than Photoshop is at the moment. :P

Your rescaling wasn't "pixel-perfect", so you have distorted pixels.

I highly recommend using a program that doesn't force you to work with "large" pixels, but rather one that lets you work with normal-size pixels but lets you zoom. Whatever you're using now is just making your life harder xP

I suspect the reason this didn't look good to you at 1x is because there was further distortion, and also because you have very poorly contrasting colours, so a lot of your detail is only visible highly zoomed in. This is something you should work on. Be bolder with your colours - it'll make your work more readable at all zoom levels.