I’d say only pre-order if you are 100% sure that nothing between now and release could possibly change your mind about the purchase.
And seeing as how there is still another upcoming beta (and the release date pushed back), I don’t quite see that being the case.
But… do whatever you want.
Pre-ordering is bad m’kay.
Based on how many hyped games turn out to be disasters (especially Halo games) in the past few years, I would wait about a month before buying. Not all the flaws and shady tactics will be seen on day 1 (although looking at all the HW2 content on the market place it is already showing a grim picture).
If u only get the campaign or more leader dlc if u preorder maybe I will but if not then no I’m not preordering