I've played both Fate/Stay Night and Fate/Hollow Ataraxia. However, like Neal advised, I'm hanging out for a review on this spin-off. All I know about the gameplay is what I've seen from the videos, and it didn't really grab me. Once it's out, and if people are saying its good, then I may import it. However, the idea of having Arcueid as my Berserker servant is quite tempting. She was awesome in Tsukihime. Otherwise, I like the design of the male Saber.
First, you don't actually need to import it (unless you live in the UK).
Second, I don't think Arcueid is in this.
And finally I don't think there's a male Saber involved in this either.
Unless I missed something....Oh yeah, we're getting this and Black Rock Shooter but no Xenoblade. I'd call it quits with gaming except that Skyward Sword is less than a month away.
Nevermind the fact that outside of an anime that covers about a third of the source material (badly), a prequel anime that isn't bothering to explain shit, and now this game that also is probably isn't going to explain shit; the only way to get a handle on this series is to read an LP, do the usual import/apply translation patch, wikipedia it, visit fansites or have a fan explain it to you, or involve illicit means.