Preordering anything in a digital format seems like an odd thing to do, unless you're absolutely confident of the product's quality and are getting some form of discount. Otherwise, why not wait, look for the best deal on release day and purchase then? All of that said, Europa Universalis IV is now available for preorder and, having spent almost a hundred hours with the pre-release version, I'm not afraid to say that it's very good indeed. I'm sure you'll be sad to hear that my preview copy has now vanished so I'll have to wait until August 13th to play, like everybody else. The video below is less than a minute long so you'd have to watch it around 90,000 times to pass the time until release.
Members of the development team have told me several times that if the company still operated as it did in the past, the game would have been released months ago. It already seems ready for release to me, but with a game so deep and broad, extensive testing can discover all manner of unexpected issues.
I hadn't realised that some of the preorder bonuses are timed or linked to having friends sign up. Paradox just confirmed for me that the reveal of the bonuses is timed but anyone preordering will receive them all, even the ones that are still hidden at the time. I'm still going to reserve a slight frown because it's my habitual look. The units and monuments appear to be entirely cosmetic, new models rather than game changing additions. So there you are!