You cant even turn without doing a 180. You actually get dizzy trying to move in that game. Divinity II > most of those Euro RPGs. That game was actually under rated.
Can't comment on Divinity as I haven't played it, but what you described doesn't really relate to how I've seen Risen work on the box - then again, I haven't played it on the box myself just seen it being played (and even if I had, give me any Xbox game - barring some fighting and racing games - and I'll tell you it doesn't work right because I can't handle the controller :laugh:).
Oh, and on topic... Yes, you should buy New Vegas. The story, general writing and the other improvements are enough to warrant the similiarity to Fallout 3 in core design - at least for a few runthroughs.