What I expected to happen was:
I would drink an invisibility potion and no mobs would see me unless I bumped into me. (I was holding no items, and was wearing no armour) This was how invisibility worked in 1.5.2

What actually happened was:
The following hostile monsters attacked me at their normal range:
zombie, skeleton and wither skeleton, creeper, and witch.

The following hostile monsters functioned as normal:
Slime (all standard sizes), blazes, cave and normal spiders, ghasts, enderman, zombie pigmen, magma cubes, silver fish

Steps to reproduce:
1. Drink a standard invisibility potion
2. Encounter one of the mobs invisibility doesn't work on
3. The mob will see you at its normal range