The latest version on only 138 mb. The paid version os 1.5 gb!
HD is best suited, as they say, for laptops.
On my 27-inch iMac, it does look nice, but the transitions are odd. All fade, only to return. Also, there is an other-worldly large supply of fish.
Screensaver mode doesn't work with the System Pref's screensaver so you'll have to turn that off.
Looks nice, but the odd transitions turned me off. To buy the full version (only $2.99) adds almost 2 gigs, which on my laptop is just too much. I ended up deleting it.