* Constantly animating with new information often leads to overload (see: marquee tag)

* Lack of affordances mask what actions can be taken by tapping on a given tile

* Lack of differentiation between the functions of different tiles leads to a confusing experience

The constant animation I can agree with somewhat.

Tapping a tile and the functions of different tiles isn't confusing because all tiles upon tapping have the same function, open the app. You can't actually interact with a live-tile in any way, though maybe you are suggesting that the animations of the tiles is suggestive that you can take an action on the tile other than open the app. In this regard, a WP tile is the same as an app icon on any other platform.

Having said that, I think the challenge in WP8 vs WP7 is the 3rd size for the tile (WP7 had only two sizes, square and landscape). The smaller sized tile does allow more info/apps/tiles to be shown on the homescreen, but it certainly clutters up the interface and makes it somewhat overwhelming.

Other than the animations, what is the difference between tiles and app icons on every other mobile OS?

Tiles convey information. I don't think iPhone does this. Android has had this since the beginning I believe. E.g., you can add a weather tile to see forecasts. Or the clock tile.