If it's uncomfortable to view, then it's too high. So ... it depends on the seating and the distance.

Here's a Houzz article on the subject, but yes, comfort is important. My T.V. is mounted over our fireplace -- this doesn't appeal to everyone, but it works for us.

[TV height[(https://www.houzz.com/magazine/how-high-should-your-tv-be-stsetivw-vs~47203714)

Please get a thimble for you pipe penetration. It is a fire safety issue. Combustible materials should never touch the pipe. And is that a wood covered pallet that it is sitting on??

Only for now, the pallet is temporary. The fireplace was installed to code, by a professional installer. It is installed with triple walled pipe and with a thimble, you just can't see it in the picture. Thanks for being concerned! Your comments are very valid.