This is a very lovely piece and it feels really fresh and original even though it's a revamp of an older piece. All the pixel art used looks really awesome and the work on the internet browser, the DeviantART interface as well as the desktop and windows interface all look spectacular and are all incredibly easy to identify as to what they are.

Some things that could be improved is the shading you used on the emoticons and their expressions. The shading itself looks a little sharp, so to say, as in the transitions between the colors, especially from the darkest shade to the next one, are a little too obvious, and they could use some work. The expressions also feel a little to static and un-alive to me. Try to add some blinking and perhaps some changes to the mouth expression on the yellow one, I think it could add a lot of depth to this.

Overall, though, this is an awesome piece that is really well made, and you've done an excellent job!

It also reminds me a lot of a deviation that I made a while ago with similar theme.