Huh? It seems coherent to me. It's organized roughly chronologically, which seems fine. Their English isn't great, but it will probably be acceptable if English isn't the standard language of discourse in your country (which sounds like the case).
You seem to have a pretty good relationship with this professor. If they haven't sent it in yet, it's probably OK to politely ask them to make the changes you want (correct dates, elaborate more on your contributions, etc.).
"He has proved that the ________ is due to the _______, which mimics the _______."
"He has strong interest in innovation and research. His ability is beyond any question."
"I strongly recommend him for the Ph.D. program of your esteemed University."
This sounds like a pretty favorable recommendation, what more do you expect them to say?
Here are Princeton's guidelines for LORs:http://www.princeton.edu/physics/graduate-program/graduate-admissions/LOR-Admission.pdf
I don't see many questions there that are unanswered by your letter.