Everything is now moving into touch. It has many advantages, it is much easier to use, faster and more intuitive to use.
If you are looking at a touch screen here are a few points to consider.
That the screen size is right.
You need one that is responsive, I have seen far too many screens that require several attempts to get them to work. If you have to press your fingers a button a lot, it gets quite aggravating
The resolution, you need good resolution, this is particularly true with many other software packages other than ours. Some have tiny buttons, and it can be a pain to press the right button. This is particularly a problem with small screens.
You will be staring at the screen, much closer than with an ordinary display so make sure that it does not hurt your eyes. I have seen some that are particularly bright, and some have poor contrast. Also, check that you cannot see scan lines. Check if you can change the video settings easily too.
Make sure it has instructions, several cheap ones I have seen come with little or no documentation.
Some cheap touch screens have what we call ghost touches. If so the touchscreen will go crazy and start doing things that you did not want. We had a client that a screen left on its own would initiate a transaction sometimes. If you did not realise what was happening, you would think that the register was in use by someone else.
Check that it has drivers for your version of windows and I do strongly suggest that you check it has drivers for windows 10 as that is where windows is now at and you may be there soon if you are not there already now.