I bought a used one in 2008, when I was coming back to firearms as a hobby and as protection provisions. I have not been able to get it to malfunction, though I did have one round of ammunition (out of unknown hundreds) that did not fire the first time the hammer was dropped on it. I've tried mixing ammo types, profiles, case materials, and ages, in the magazines and it still runs and runs. Shoots well, and hits where I expect it to.
I carried it for two years until I happened across a Kel-Tec PF9, then a highly-sought pistol, and bought it. The PF9 is harder-hitting than the Bersa, on both ends, and not nearly as enjoyable at the range. I still find the Bersa to be a great pistol, though its relevance has been diminished by several factors, including the pocket-.380 class, the micro-nine class, and the new interest in double-stack micro-nines. Other .380ACP pistols released after the Thunder, such as the Ruger LC380/LC380s, the S&W Shield-EZ .380, and the SCCY CPX-II, have also further diminished Bersa recognition.
For a solid, all-metal, DA/SA hammer-fired .380, though, the Thunder series is an exceptional value.
Incidentally, I also bought one in .22LR a couple of years back, also used. I only got that one out to the range once (so far), and it wasn't that reliable. It looked not to have been broken it; maybe the previous owner bought it and then couldn't source any ammo at the time.