I think it totaly depends on your current situation. If you dont have any hit whats so ever and you seem to be lacking in the threat department, then it would be a great investment (what good is stam when you cant hold the mob on you in the first place)
One option for some really easy hit rating is getting the poison vial from R&J in Karazhan (there's also a blue trinket from a heroic with about 30 hit rating on it as well). A trinket slot can be swapped out without losing many stats at all while you gain over 2% hit. Trinket slots in general are just the best way to get a large amount of any one stat that you may feel is necessary for the fight you're going into.