I am of the opinion that any course you have on your resume cannot be a bad thing. Your initiative to take a course to increase your knowledge can only be seen as a positive thing to prospective employers.
I cannot speak to the value of the ESRI course but it will probably be of high quality. It will, however, be focused on python implementation within the ArcGIS environment. It will not teach you programming best practice techniques that you will gain through a university course. You will most likely gain knowledge of how to implement tasks that will help you in your working environment.
I recommend reading up on Python and practicing as much as you can prior to the course to get the most out of it.
Here is a good source that helped me learn the basics of Python. Some other sources to help you out can be found here:
- http://www.python.org/
- http://docs.python.org/tutorial/index.html
- http://www.tutorialspoint.com/python/
- http://en.wikibooks.org/wiki/Python_Programming
EDIT: If you can get your current employer to pay for the course, all the better.
Good luck.