It was beautiful. Olivetti had great industrial design in the 1960s and 1970s. Their typewriters and calculators were works of art, and you can often find them today in the collections of major modern art museums. Olivetti tried to get into computers, and even had a good-looking IBM PC clone. The nice design didn't help.
The Mathatron came out a year earlier, in 1963. (http://www.oldcalculatormuseum.com/math8-48mII.html) Unlike the Programma 101, the Mathatron had trig functions built-in. The Mathatron had enough compute power that they offered a remote-access shared programmable calculator with a phone modem. (http://www.amazon.com/Wright-Mathatron-Computer-Calculator-M...)
The shared-calculator approach reached its peak with the Control Data Remote Calculator. (http://www.oldcalculatormuseum.com/a-cdc-11-65.html) This was a scheme to have 2000 calculators share a CDC 6600 mainframe computer, an excellent supercomputer of the 1960s. It was not successful, and surplus units appeared in the movies Soylent Green, Westworld, and Marooned.
None of these were very powerful, but the alternative at the time was slide rules and trig tables.
It wasn't all-electronic; that memory used _sound_waves_ to store bits. That six meters of wire probably meant that reading a word, worst-case, took about a ms (assuming a fairly generous sound speed of 6km/s), and about every instruction read from and wrote to that storage. This being the first of its kind, the implementation probably would be worst-case for both reading and writing (wait for the 'start of memory' marker, count bits until the ones needed come along)
And of course, it had to read its instructions from the same wire. I guess 500 instructions per second would be an exaggeration of its performance.
Google led me to http://en.m.wikipedia.org/wiki/Delay_line_memory#Magnetostri.... It isn't audio, but a torsional wave, and Wikipedia claims a delay in the order of half a millisecond.
The M24  worked well too. It had a good display, particularly with the black and white monitor. An OEM Logitech mouse could be plugged into the keyboard.
I recently found this blog entry showing a lot of beautiful ideas http://ceciliapolidoritwicedesign2.blogspot.fr/2011/12/sotts...
When Olivetti was in financial troubles, a task force of government people and people from other industries (FIAT, cited in the video at "https://www.youtube.com/watch?v=oYB2oBc1BpA", linked in another post) gathered together not to help Olivetti, but just to sell it.
They just did not understand what they were dealing with.
There is a Programma 101 on display at the Computer History Museum a couple of blocks from the Googleplex. I was walking along a glass display cabinet with my kids, saying, "I used that one, and I owned that one, and that one...," when there it was in all its ancient glory.