I'd say the worth of a collector's edition game depends on the quality of the specific game's collector's edition packaging. For some games, such as Skyrim, you get a lot of really cool extras along with the game. But for some collector's edition versions of games, all you get is a tin case and perhaps some extra DLC tagged on to it, which in my opinion is not worth the extra money at all.
So it really depends on the game and how good the collector's edition is. For most, I'd say it's not really worth it. But occasionally they'll come out with some really nice packaging and extras to make it worthwhile.