Do one thing for me, check where it was assembled at the back of the phone, and pull the spen out and check that too, opposite side of the logo - My previous 3 with build quality issues, were vietnam assembled, this one ive got which is perfect is a mix of korea and china.
And yup its perfect, no movement, no screen gaps, no heating issues even with my SD card in (transcend thing).
Edit - signal is a difficult one to answer, on Voda in my house never really get more than 2 bars, but outside full bars all the time, never had an issue with it on any of them.