I hate to think how many hours I have spent playing Bethesda games,  considering I have already put more than 600 hours into Fallout: New Vegas the total must be more than a couple of thousand. For me the magic comes from the "user mods", some of which are incredible. New Vegas started off unstable for me too but after adding the 3GB+ mod, sorting my load order out and using FNVEdit to create a merged patch I very rarely have a crash.

I'm really looking forward to Skyrim but I do have worries about the new engine being less "modable".