HP 35s Scientific Calculator

This is a great calculator. As a young engineer preparing for the PE exam, I am very impressed with this updated classic calculator. HP and RPN is the way to go. Only one problem. HP does not include a printed owner's manual. You have to call HP to order one. I look forward to being able to maximize the capabilities of this calculator when the owner's manual arrives.

This is my first HP calculator and I was looking forward to buying a quality calculator after tossing out Sharp calculators every year or two, when the LCD's went south. I appreciate the solid construction and the "click" when you enter a number, giving feedback that the number is entered without looking at the display. I've had my fair share of using the undo-button on cheaper calculators with flimsy buttons, once I notice that I missed entered a number.
The ENG button for converting to engineering notation is a great welcome, too, and I even like the RPN notation (which I find pretty neat as a newbie to HP's). All of this said -- and to my great dismay -- I discovered that base conversion on the HP 35s is an absolute nightmare. How many ticks does it take to get to the center of a Tootsie Pop? One, two, three ... that's how many operations it takes to enter a hex number on the 35s.
I work with embedded software and, from time to time, need to do a fair amount of calculations in hexadecimal mode (base-16). The 35s assumes that ALL number entered are in decimal format, even when you enable the calculator to output in hex format. Each and every time that I need to enter a hex number, I have to (1) enter the number, (2) enter into base mode (press the blue button and then the 1 button), and finally (3) convert to hex (press the 6 button). What a royal pain in the butt.
I plan to return this calculator. Maybe I'll try a TI calculator this go around.

I bought the original HP-35 back in the early 1970s. I loved RPN then and I love it now. I don't understand why HP nearly gave it up after Texas Instruments moved into the market. Anyway, the HP-35S has everything I need and more. My only criticism: Why isn't there a help feature? You should be able to press and key and get instant help on it.

This is truly a "nerd's" calculator. It is a calculating workhorse. It was designed to separate the true math/engineering jock from the weekend dilettante and mere poseur, and the price certainly discourages amateurs--in other words, it is not for eighth graders. But, I don't know, maybe some suburban soccer-mom might buy it so little Britney can do her algebra homework.

"Because she deserves the best"--BIG mistake lady.

Sure you can use it to file your tax return, but make no mistake, you WILL spend some considerable time beforehand learning to just calculate percentages.

But if you decide to man-up, I have two words for you: ALG Mode.

There are already many good reviews here covering most of the main points, but here's my 2-cents.
I have used HPs with RPN for many years, including 32S, 42S, 48gII, and 50g. The 35s is a mid-level model like the 32s, but with a few improvements mentioned by others. I especially like the easy entry of complex numbers using the "i" (or shift-theta) key. But the main thing that is good about this calculator is the return to good manufacturing. No more defective keys like those that plagued the 48g series during the "bad years". The 50g I have seems to have fixed this issue at the high-end too.
So why not get the high-end 50g graphing calculator? Because the 35s is simpler and more efficient for basic calculations. Yes - it does not have multi-character labels - but it is much easier to store and recall basic variables than using the 50g (fewer keystrokes and no need to remember more involved programming constructs to make such simple operations work ;-)
Pros: good "upgrade" of the 32sII. Good keyboard. Display has good contrast. Nice for simple complex-number crunching.
Cons: Display of complex numbers is more difficult to read than on the 42s. Definitely NOT a 42s type machine.
But maybe soon the same engineers who produced this nice upgrade/replacement for the 32sII will do the same for the 42s. Please !!!
Thanks HP, for a great product.