Its been almost a week since I got my phone and I agree with the OP.
About the charging times, yeah it is kinda slow, my Xperia tablet Z is the same way, anyway battery life is awesome so I can go thru the day with no hassle and let it charge during the night.
Double tap works fine for me, sometimes it doesn't but I guess the screen is so sensitive that maybe it senses my leg when it is in my pocket or maybe it gets confused somehow by sensing the fabrics of the pockets, I don't know. But when I have it on my desk and I double tap it, it works all the time. I also make sure that the screen is clean of fingerprints, grease and oils.
Notifications volume should be separated from the ringtone volume like other devices, it is also very low.
Lastly I agree that a Reset button on the power menu should be available.
Even with these issues, this phone is perfect for me.
LG G2X (rooted, retired)
Samsung Galaxy S2 (Unlocked and rooted, retired)
Sony Xperia Tablet (Stock rom, awesome device)
Sony Xperia Z2