I worked at Sun labs and used a Sun Ray daily for a whole summer. It worked...OK. Definitely not "Incredibly well". We had a network of a few hundred Sun Rays and two E10Ks backing it. More than a million for the servers and $1000k a piece for the Sun Rays was not cheap. Basically any $1000 laptop was more powerful, without the need for a crazy powerful Sun server. The experience of taking out my ID card, walking down the hall to another cubicle and popping it in and getting my session was magical. But I did that less than once a week, so I don't think it was overall worth it. The Sun Rays also had a pretty crappy LCD, about 1-2 years behind the SoTA.

It was a cool idea. It will keep coming back again and again. But at Sun's price points around the early 2000s, it was a loser, and I actually agree with the market in this instance. Sun Ray was a flop.