Never buy a new car, and never* buy a new game.
*
almost never.
I did buy BF3 pre-release, and I bought the premium pack but I waited until a sale for that. Loved every one of them, even the CQB maps which I didn't think I'd enjoy. If I hadn't bought the prem-pack then I'd have hated to be stuck on just the base maps whilst all the other guys are having paid-for fun on the others.
I wish I could buy an MTAR-21 though.
I've also bought the Arma III alpha, as the current price is so much better than the post-release price, and it just looks great.
I'll be buying BF4, maybe not pre-release, but I'll be buying it anyway. As for MoH - it's always been crap (imo) but they entice you with the BF beta - some fall for it, but not me.