Suppose that depends on how much you enjoy your BF4 experience so far. If you're more casual you may want to wait till more of the expacs are out so you can see what you're getting before jumping in. Me I bought it day one and have no regrets, but I knew going in I'd be playing the hell out of the game and almost 300 hours later I was pretty much dead on.
Seriously though, EA sucks and they should stop charging double the standard market price for their games.
That's horribly one sided. pretty much every company that offers DLC does the same thing.
Not to mention the deal was pretty much the same as far back as BF1942. You didn't have a preorder setup with perks, but by the time you bought both expacs it still ended up essentially the same price.
Uh, that entirely depends on how much he plays and what he wants to get out of the game...
I've got over 150 hours in and it's pretty clear Premium would be worth it. We already know about the first two DLCs, and Premium grants access to 5 of them (technically 4 more if you pre-ordered and got one free).
Now if he's only played like, 20 hours and doesn't really get into the game for the long-term, then Premium may not be worth it.