(I somehow misread above post as being about FP3. Rest of post is kept as-is.)
It is too early to tell at this point as the sample size is too small, and we don’t know if/how some of the known issues are going to be resolved.
Here is a list thus far. This is just a placeholder post of some known issues in FP3. Be aware that reports of issues need to be confirmed by the community and customer support. Therefore, everything in this list is UNCONFIRMED and heresay until stated otherwise.
Weak light FP3 photos - #3 by Roboe → other source: Tweakers review.
Bluetooth Performance - #6 by WePhoton → other source: several reviews (?)
LED notifications do not work → multiple users confirmed the issue (LED can only be used to notify about charging status; might be solvable via firmware update)
Headphone Jack/plug doesn't work → confirmed by two reports thus far
Fingerprint → the module can be removed, fingerprint sensor is known to not work with greasy/wet fingers (which is normal behavior)
Hidden WLAN SSID is not reconnectin when in range/doesn't work on initial setup → confirmed by one user reports thus far.
NFC issues - reading cards and payment → confirmed by one user reports thus far.
Battery life too high → battery life lasts longer than expected 
multiple reports about that.