Spoiler: 



Retrieved the images via:
http://cdn.dota2.com/apps/dota2/images/items/<name>_lg.png
Where <name> was provided by the Steam API via GetGameItems.

1. The newer item icons (mango, BoT2, lotus orb, etc especially glimmer cape) are smaller in height.
2. The recipe version of those items seem to be missing.
3. Recipe version should be more distinct. Currently they are identical (with the exception of phase boots).
4. A lot of unnecessary recipe images. Many of those items don't require a recipe to be built.
5. There is an icon for ward&sentry but not sentry&ward.