I received my iSub Apex yesterday and have been using it and loving it. The air flow options are wonderful. I love the top fill but I have to say with my old eyes it is a bit hard to tell when it is filled enough if using lighter colored Liquid, but I think once I am used to it that will no longer be an issue. I love the air flow option on the tip part and am so glad that the tip is interchangeable. I slipped the glass looking one right on but other drip tips fit nicely as well. The flavor I am getting out of my liquid is outstanding. I don't know if I can comment on the quietness of the tank as I am hard of hearing so they are all quiet to me.
Here is a picture and if this little review should not go here I will be happy to move it to anyplace I should. Here is a little pic.