Lets break this whole thing down before we shush everyone.
Basic pixel artMs paint: Easy enough, but you only get three undos, so making mistakes is incredibly annoying.
Any other program: Easy
TransparencyMs paint: Can't do it, but you can use magenta if you want to. Semi-transparency and blurring is impossible.
Any other program: Can do it.
Brush sizesMs paint: A few presets.
Any other program: Allows you to scale brushes freely.
Selection toolMs paint: Annoying and limited.
Any other program: Useful.
Color selectorMs paint: Good enough once you learn it, but you have to delete one of your preset colors to use it.
Any other program: Simple and easy to use.
ZoomingMs paint: Has a few presets.
Any other program: Allows you to zoom freely.
LayersMs paint: Nope.
Most other programs: Yes.
GridsMs paint: Nope.
Most other programs: Yes.
Final verdictAnyone still using paint is just being stubborn. Its useable, but not nearly as good as, well, anything.
If you want to use it, then go ahead, but I highly recommend that you get something else, like
Paint.net or
GIMP.
Now lets not get any further off topic.