Looks pretty damn good for a first attempt. One thing with TIG in general and aluminum specifically, is that to get the nicest finished welds, you want everything as clean as you can get it. That will take care of a lot of the stuff floating up in your puddle. Like operating room clean. Sand or stainless wire brush the oxide layer, then wipe down with acetone. Do this right before you weld.
Also when you end your welds, taper off the power and add a little extra filler to prevent the little crater at the end. It's more than just looks, it is a place where cracks will start from that crater. Keep up the good work and have fun.
Long arc, short arc, heliarc and in-the-dark!