I ran NEXTSTEP 3.2 and I think, 3.3, on both 486 DX2/66 and original NeXT hardware. At one job I ran on a 25Mhz Mono slab as my daily and only machine. I did Web surfing, email, used VarioData for the home-built sales/contact system, etc.

There were some pieces that were slow, but overall it was a fantastic experience. The "Shelf" was great; I would store commonly-used docs there, reference materials etc.