How well does the game run with that card?
Well, it really depends. Also, the CPU and the RAM are probably important for procedural terrain generation. I have an AMD Athlon 64 and 4 GB of RAM DDR3. Of course, in deep space, FPS is maxed out. When closing from a star you have some slowdowns, probably because of the fancy artifacts (that you can deactivate).
On "complex" planets, the first picture I posted is a "worse-case scenario" with an atmosphere, complex procedural terrain, and even rings. That gives 9-10 FPS, and if you want to enjoy all the terrain details, you have to move slowly or wait on a spot for every layer of detail to be generated. Still, it is very "playable", as you control a free camera. You can also roam under the oceans, when present.
The Moon with terrain loaded from heightmaps is much more FPS-friendly, also the lack of atmosphere helps. In counterpart, it is much less detailed when seen from the ground. IMHO what is lacking are procedurally-generated small rocks, like you can see in KSP.
Small bodies like asteroïds are unsurprisingly the most FPS-friendly, but of course there is not much to see there.
Notice that a toolbar you can access at any moment allows you to toggle "display/hide" nearly every feature : terrain, atmosphere, clouds, water (rather "liquids" !), stars, planets, etc etc... This has an immediate effect on FPS.
Also there are a ton of graphic settings you can adjust, including the complexity of generated terrain (max detail layer level), so you really don't need a super heavy config to enjoy it. :2cents:
Oh and using BitTorrent and fiber optics, the 10 GB of download was a breeze. Also when you're familiar with Orbiter, installation of extra textures is quite straightforward.