I actually never used that feature, so I just checked it out. It can indeed show animation for a set of tiles. You chose the first tile to animate, the last tile to animate, and can change the speed. If you want to do anything really complex with the animation (jump around between tiles, animate so that it reaches the last tile and goes backwards, or set a specific speed you can't. You can make the animation faster or slower, but you can't set the delay in 10th of seconds or anything). Additionally, it takes a couple key strokes to set up the animation (arrow over to the first, press {, arrow to the last, press }, press control a) so if you want to animate a bunch of tiles really quickly you won't be able to. However, I don't know if any of those things are necessarily that important. The program is enough to get an idea of how your tile or sprite will look in your game. I think the animation features should be sufficient for imagining what your game will look like.

I have to say graphics gale is the absolute best... WAY better then ms paint...

not to mention its free... But some of the advanteges of graphicsgale over ms paint are

~you can do animations
~sprites can have a transparent background(ms paint cant do that)
~you get a graph
~RGB sliders
~alot of good extentions
~a way easier workspace( In ms paint to get a color of the canvas you have to press "dropper"
in graphicscale you just rightclick the color, and lots of other things)

and plenty more

I dont know the site, but searching for it always finds it for me...
but the site is in japanese so to download press the BLUE button a little down the page.

the actual program is in english(weird)