Quality of material

That's a very loaded (but reasonable) question.

I think the quality of the models is very good. We have a reference list that gives a link to every Shapeway's model in Decks A to E in the Naval Modeling subforum.

forumini.boards.net/thread/205/poseidon-neptune-kraken-ryujin-shapeways

People differ on what materials they prefer.

The frosted detail give you the smoothest and sharpest models, but it is fairly brittle. The White, Strong, and Flexible (WSF) has a somewhat fuzzy surface, but it the most durable. The black HP plastic is smooth and not quite as brittle as the frosted detail, but it is very expensive. The guys that buy them mainly to collect them and not actually play with them usually go for the frosted detail. I get mine to be played with so I favor the WSF. I have a hard time even painting the frost detail without breaking off bits of the model. We have worked out techniques that help to smooth the WSF somewhat, but nothing can make it totally smooth. The WSF is also available in "polished" to smooth the surface, but the process also loses some of the detail.

Those are the main three (four if you count polished WSF) materials used by most of us. All I can really suggest is buying a couple of models in each and see what you prefer. That is what I did early on. The other important thing to say is the 3D printing process is still pretty primitive. I never get totally identical copies of the same sculpt. For one thing, the models will differ greatly on detail and the smoothness of curves depending on whether the model was oriented horizontally to the base printing plate or vertically. There also seems to be at least a little "art" to printing because some printers seem to do better than others even in the same material. Fortunately, Shapeways is pretty good about getting you a replacement if the print is really bad.

I hope this helps. You can find more information in the Naval Modeling subforum. And a lot more opinions!