This is D'aww, though why is it shipping? People are beginning to twist everything into shipping anymore. In fact, the only reason I mention it is because of what you said in the description. For shame you fans, for shame.
It looks like Pinkie always knows the perfect cure for whatever has a pony down. The ponies look great, especially Pinkie Pie with the stretchy effect making it perfectly clear that she just popped forward and came to a full stop, waiting not long at all for Twilight to crack a little smile.
Great work on the coloring too, especially the watercolor-ish effects (which probably have a better name) to make the translucency show so wonderfully; it also works great on the ponies' manes and tails to give them more depth, especially Pinkie's fluffiness. Also the balloon colors lighting up their heads was another neat effect, sort of party lighting on the go. And the big happy smile is just fantastic.
Oh my goodness! This is absolutely, positively, super duper adorably cute! This makes me want to carry balloons around, like those long ones that can be twisted into shapes, and use them just in case someone could use some cheering up.