The experience I've made with Olivetti typewriters wasn't that good really. They are lower quality then many of the competing brands at the time (especially against the German machines, no comparison), and didn't really offered anything new either. They are nicely designed and offer some comfort if use, and many of their portables are very compact too while offering many of the features of larger machines, but they just don't last, and don't age very well. For example the famous Lettera 22's and 32's. The paint job is terrible and they are completely made of injection molded zinc-aluminium stuff, I think. Its very brittle and the entire machine is constructed out of moulded and sheet metal. Nearly all I've had the rubber was bad and the feet had broken off. Also the cases are incredibly cheap, the zipper is broken nearly on all of them. I haven't really made much experience with the older machines tho.
That being said, they are still nice and convenient to use, which is why they are still so popular.