I'm typing on a BTC 5339R-0 foam and foil keybard. I purchased it for $6 about a month ago. I have not tested it until now. So far all the keys seem t work although I'm not a huge fan of linear key action. I also do not like the placement of the 'macro' key as I keep pressing it instead of 'control'. However I will admit that these keys make a pleasant sound as they slide up and down.
I would expect longevity to be a problem if I were to use this keyboard regularity. The foam will degrade with both use and age resulting in poor key feel and response. Frankly I am surprised it is intact, considering the age of the keyboard.
N-key rollover! An unexpected treat. Finally a keyboard I can use to play Star Control 2 Super Melee in two player mode. this has always been a problem because player one's controls are nm,./ and player two's controls are 12345. It's actually not a bad arangement except for all the key blocking.
The 'macro' key, according to the only document I found that mentioned it, sends control+shift. I have not confirmed that.