I like working with low resolution sprites (ie. 8x8 or 16x16) and then I set the layouts to a 200% zoom. But with Construct 2 and HTML5, i'm getting blurry sprites.
Unfortunately it's up to the browser how it displays stretched sprites. Chrome seems to use nearest neighbour, but all other browsers use bilinear, and I think Chrome might switch to bilinear when they enable hardware acceleration too. There's nothing in the standard that lets you override it. You might just have to draw all your graphics 2x - PNG should compress away the difference in filesize anyway.
also just noticed construct's zoom (crtl + mouse wheel) zooms in by 10% over the previous zoom value every time (100% -> 110% -> 121% -> 133%...) so I can't zoom to round numbers (200%, 400%) and this is really annoying.
Hold ctrl+shift as you scroll the mouse wheel, or use the zoom buttons in the ribbon.