When I was first learning Z80 ASM, it was a big hassle with all of the batch files and DOS commands and whatnot you had to create, organize, and check if you wanted to assemble a program. I had no idea what batch files were, and was quite irritated with the inability to assemble programs until I understood batch file creation.
With Assembly Studio, this hassle was gone. I have used the software for a brief time, but I switched back to TASM after I figured out how to use it. I must say it looks and feels a lot like Dev C++, only with the ability to allow you to edit sprites and graphics easily.
It has tons of features that allow you to easily find and correct errors, and it colorizes everything so you know what's what and what it does. The only real complaint I have about it is that the code editting window completly strokes out on me if I select the sprite edit window in a certain order, but that is probably my computer, not the program itself.
I will probably write all of my games in the future with this program.