Besides the great averia of talking during davening,one has to realize that he is Chotei UmachtI.
In Addition, he is being mevatel the mitvo of answerng Omein which the Sifri says in Haazinu, is DeOraysa!!!
See the Netziv in Haamek Shaalo.
The SiDur Hachida, brings down that when a person taks during Magen Ovos on Friday night,
his punishment is that after his Petira the malochim lift him up very high, and then let go.
The Zohar CHodosh on Rus, says that that if a person misses an Omein, he is burnt in the 3rd level of Gehinnom.
The Levush was once put into cherem by his Rebbi, for missing an Omein to a childs brocho!!
Rabbosai, be zohir!!!!!