I feel like this has been posted before... too lazy to look for it.
But please.. I'm tired of hearing this same question over and over again.
If you like battlefield and plan on buying the DLCs, then by all means, purchase premium, you'll save money.
If you're so-so about the game and don't really care about extra maps and guns because you have fun with just the in-disk stuff, then don't buy it.
Sorry if I seem.. (can't find the word for it) but seriously, if you're going to buy something, please read about it first