I just updated to iOS 9.2.1 on my 5S yesterday afternoon. I didn't notice any issues last night, although my battery drained much faster than normal doing nothing more than texting. Literally lost 30% in an hour.
However, this morning, my Touch ID suddenly stopped working after charging all night. I hard restarted my iPhone, and Touch ID seemed to work fine for a few mi Utes, then stopped again. This time I discovered my Touch ID settings had been wiped out. So I tried to set it up again, and kept getting an error preventing me. Another hard restart and no difference. Backed up and restored the iPhone, and the same. I'm waiting now to reset the iPhone to factory default to see if it's a hardware problem, before restoring again.