Summary: I had one in college in the 1980's. I loved it. However, the HP quality that I expected was not there. The keys are mushier. Still, it works fine. I just don't have the confidence that I entered numbers correctly, without checking the display.
Summary: Great calculator for less than $20 at iTunes store. Get virtual calculator for use on phone and tablet and save lots of money. Have had physical HP 12C calculators for over 25 years (and they all still work). Please be careful of price gouging, as the calculators should be about $100 for a physical calculator.
Summary: I am a true fan of the HP 15C (the original). However, when I tried to calculate sin(45), it gives me the answer as if I were calculating it in radians, not degrees. I tried to convert to degrees, the display indicates I am not in radians, but the answer is still 0.8509 instead of 0.7071. I just wonder how many other functions operate incorrectly. Thankfully, I remembered sin(45) from 30 years ago in college so I caught it.
HP-15C is a Great Calculator, solidly built and easy to use in your hands.
3 August 2014
Summary: This is the ultimate 10 series calculator from HP. It is so good and popular that HP did a special edition re-manufacture years after it went out of production. The original HP 15C is heavier, solidly constructed and lasts. The "landscape" orientation allows for two thumb operation while holding it in your hands. RPN makes for really fast calculations without brackets or an equals sign.
It is like a "Linus blanket" (Charlie Brown reference)
John P., Amazon
19 June 2014
Summary: I am lucky to have hidden my original 1980's HP 15C ,from the ex wife on a cleaning out the house weekend whim. I recently pulled it off the bench and put it back into the game. I decide to go back to academia at a latter point in my life. I am the oldest in the class. Most of the others have bloated function graphing calculators, but with RPN I am able to come up with results fast enough to seam omniscient to others.