Wow, I'm quite surprised by all the negativity about this. There's been a number of DCS modules with the option to pre-purchase, and you should all know by now that release dates can get pushed back. This is ED, not EA, their release dates are based on the product being ready to play not a corporate decision to please shareholders.
I'm hyped that we have something solid now, and I'll be buying the F-5 tomorrow morning. Hopefully it'll release early July, but if not then oh well. I still can't wait to fly it.