The spell as written gives all the benefits of 3/4 cover, including the protection from AoO and the Reflex save.
The D&D FAQ says, however, that the spell should only give a +7 cover bonus (not cover) to AC. If you play it this way, it does not make you immune to AoO nor does it provide any bonus to your Reflex saves. This has not been changed in the errata so far, just the FAQ, although WotC considers the FAQ official.