It isn't easy being a Dragon Quest fan in the west, the games are scattered on a whole bunch of consoles and some never even get localized in English.
So having Dragon Quest Heroes appear on Steam is excellent news, if it ends up being successful enough perhaps the rest of the series will follow and we'll be able to play them all on one platform.
The release date is set for the 3rd of December and until then there is a rather small 10% discount for pre-ordering. The usual advice is still to wait for it to launch and see if the reviews are positive, the 10% price reduction will be a small consolation if the unfortunate happens and the game releases buggy or broken.
Keep in mind that this is not a part of the main Dragon Quest series, it is instead a spin-off with gameplay being most similar to that of the Dynasty Warriors franchise rather than the usual RPG style you might associate with Dragon Quest.
That doesn't mean the game is bad however, just different. The reviews from what I've seen are generally positive but your enjoyment will greatly depend on whether you like the Dynasty Warriors "one vs a thousand" battles or not.
The port is being handled by Koei Tecmo which as far as I'm concerned is reassuring news. I've only ever played a couple of their ports but they've all ran perfectly fine despite my PC back then not being the greatest. Hopefully the same goes for Dragon Quest Heroes.
PC version will launch with what is essentially the digital collector's edition content, that is with two extra maps and a bunch of slime themed weapons. The weapons I don't really care about but more maps are always welcome.
With all of that said, I'll leave you with the trailer (albeit for the PS4 version):