I have used it a small amount. It's a very interesting tool that I feel is better at getting your feet wet in homebrew developing rather than helping to create the game you had ideas about in your head. It's quite powerful for what it is, and it really can do a lot of things. The map making tool section I love, it's quite easy to make nametables, but in the end it will still take a bit of knowledge about ASM to do a lot of things with it. I recommend it for anyone wanting to experience making a homebrew with simpler functions, and to see if it's something they would be willing to learn ASM for to do a lot more with. Not knowing a ton of ASM, I can't give an opinion on how it affects any sort of advanced homebrew making though.
Vaosu's post in NESmaker by the 8bit Hero guy. Anyone try it yet? was marked as the answer