I don't think I've ever had a crash with Risen3D. It runs very nicely on my not-too hot machine (2.8GHz P4, 1GB Ram GeForce 6200, WinXP). I tend to run it with models and hi res textures enabled at screen res 1024x768. I haven't found it laggy or slow at all. One of the things I like to use it for is to play older maps to give them a bit of a "new generation" look to them. Risen3D handles that very well IMO. However, I've also been playing HeDRoX on it recently. It certainly has a load of lines crammed into a small space and Risen3D hasn't had a problem with it at all.
http://www.doomworld.com/idgames/index.php?id=13458
Installation of Risen3D was easy enough (it has an install exe) and most of the additional packs and R3D specific maps come as self extracting archives with correct path information built in, so installing them is easy too. There is quite a lot of downloading to get everything that you might want, but it wasn't difficult. As I said, I find the launcher more friendly than Snowberry too. There is a "quick launcher" available as a separate download, but I prefer the standard launcher.
Aside from anything else, downloading and installing Risen3D is worth it just to marvel at what Sitters has done to visually integrate models and Doom architecture so completely in his maps. Genetic Disaster and Doom Dragon in particular show this off very well. Sometimes his maps (particularly the older ones) are quite confusing key/switch hunts (less so with the two mentioned) and they tend to be pretty tough too, but they are definitely worth playing.