You will go through a security check when you transfer at Istanbul, but no passport control. The new airport is massive, not well-signed or serviced, and if your incoming flight is a bit late, then you will have to rush somewhat to make the connection. Look for the special passage for short transits. At least if travelling Turkish Airlines, expect no help at all in making the connection. Just try to find the transit desk! And don't expect free wifi in the terminal.