What happened to the I PHONE,s standard/quality?

What is going on? •I can no more take screen shots and send it via whats app, etc. My screen just freezes! •My reception signal very very bad! ....it is cut off/fall down or my friends complaining that i am going off line; my battery going down very fast although all t pages are closed on Safari; I was ALWAYS such a dedicated I phone user BUT HAVE DOUBTS ABOUT MY NEXT PHONE PURCHASE! I AM SO DISAPOINTED!