Beware not to buy HP Prime, if you are engineer!

[dmmaster]

It is fast, but it does not mean that it is better. Software, content and usage are more important and valuable than colors and touch-screen (for engineers). Professional user interface allows to deal with content. Keyboard layout of HP49/HP50G allows to stay in focus on math/finances/sciences/... (i.e. content). Touchscreen is good, but it could be sometimes a small barrier, it makes it difficult. In comparison, you can give a very simple mathematical problem + Wolfram Mathematica, and students can't find a solution. Many students have troubles with usability of software's (mouses,...). This is just a fact. Maybe, newer generations of students may have sometimes more conflicts with numerous distractions.
Modern interfaces and usability will actually often distract and bring students away from their main learning goals.

Quora gives here a good definition, just quoting from Quora:
https://www.quora.com/What-are-the-main-...d-HP-Prime

Quote:The HP50g is the last of the “professional calculator.” The HP50g includes a periodic table, SD card slot, better unit conversion, and the old-school HP scientific/financial equation library.

The HP Prime is more of an academic/mathematician young brother. It offers inverse probability functions, better matrix input, colored graphing, and spreadsheet support.

It is really your call. IMO If I had $150 to blow on a device, I would check Wally World for a netbook.

Quora gives a clean definition of the usage of these 2 graphical calculators:
- HP Prime: for "young brother" and for school
- HP50G: for professionals, engineers, and for scientific/financial interests, for sciences.