I've been using Vue for a little while now, and here's what I've found. Please note, though, I've used Vue alot more than TG2:
Ease-of-Use: Vue (For some reason, at least to me, Vue just
feels comfortable when layout out scenes. Perhaps that's partly the GUI, but I can't say for certain. At this stage, though, Vue seems to slightly outweigh TG2 in this aspect)
Stability: Varies (Vue, for smaller renders on a single machine, works fine. My chief gripe is with the renderfarm module, HyperVue. The amount of grief this module has given me (such as failing to connect to other computers due to in-scene texture scales, etc) has really bugged me. That having been said, I've never done an A3 render with TG2, so I can't speak from experience when it comes to that.
Realism: Ughhhh... well... 'it depends' is the best answer I can say at this stage. I've seen some incredible things done in both. But I suppose the question is more along the lines of Global VS Local:
Global: TG2 (TG2 hammers Vue into the ground when trying to create seamless terrains or high-altitude shots. Set up a procedural planet, tweak the atmosphere and place your camera - that's the groundwork done. Whereas with Vue, doing the same thing (again, for me personally) is like pulling teeth. Vue
does have procedural terrain objects, but... well, I've not succeeded in making it stretch over the horizon and still look right yet.)
Local: Vue (This seems to be Vue's primary purpose - placing individual mountains and trees to get that 'just-right' postcard look. Or, at least, that's what I use it for.)
Pricetag: *gulp* (Okay... this is a funny one for me. I bought Vue 6 when it was 50% off (which is pretty much what made up my mind to get it in the first place), and, yeah, it's done a fair job. But then Vue 7 came up. To benefit, I had to fork out the same amount ($200USD) that I'd already paid for Vue 6, and I'd only just bought it less than a year earlier (closer to, well, six-eight months). So I'm slightly biased in this regard ~ I almost boycotted Vue altogether after that, and I'm still torn between getting Vue 7 and just getting TG2 and being done with it
But again, that's based entirely on my personal experience, so take it with a grain of salt.)
Well, that's my Vue-related life story - hopefully that gives you a little extra information to play with when you make your final decision. I apologise if it seems too slanted.
~Shashin