Is it true that this perk is bugged? Basically I read that once it is activated, it renders all other block perks obsolete or something to that effect.

Seems to work fine for myself, I'm sure there might be someone who has that problem though if you heard it

The deflect arrows perk is bugged in that it gives you maximum shield protection from everything rather than just arrows, thereby rendering all other protection perks like shield wall pointless. there is a fix on pc for this here http://skyrim.nexusmods.com/downloads/file.php?id=7740 until bethesda patch it