I've clocked in a few hours with it now (and about 40% of the trophies). It's seriously the best "Sim" racer on Vita right now, though granted there's not much competition and I actually think it straddles the Sim vs Arcade balance perfectly. The pocketgamer review pretty much sums it up perfectly for me (I'd even give it the same score). Definitely in my top 5 Vita games of 2013.
I love the tension when you're hurtling down a dirt road right on the edge of losing control as it takes very little to completely lose it and total your car (luckily the rewind function can help here) but at the same time, I don't think there has been a rally game since Rallisport Challenge 2 on the Xbox that got the handling so right. I prefer this to DIRT 3 as a Rally game. The handling is fantastic and the visuals look fantastic to boot. There is so much detail to the environments compared with WRC3.
WRC 3 was 6/10 Vita title and WRC 4 is most definitely an 8/10 title in comparison. It really is that much of an improvement. I really need to try Moto GP 2013 now too!