Yes the heating issue is there. After taking 10 snaps the phone starts to feel hot around 42-46 degrees. Overall, there is no remarkable difference between Z1 and Z2 whereas G3 against G2 is huge.
If you look at my history for the phone from last two months, i switched from S5 to m8 to lg g pro 2 to xperia z2 to lg g3. I have used all, i can even describe real my personal life issues with these sets( on stock Version).
S5 --> cam and screen are excellent, Extreme ram usage, 1.2-1.4 gb out 1.8 gb already in use at start. Not a fan of big chromes, overall 8/10
HTC One M8 --> Build, screen and speaker excellent, cam underpar, not a flagship cam, cam glass gets easily scratched and nano sim slot is daudgey (if you cut normal sim in to nano sim via tool , it is about 0.5 mm thicker than normal nano sim, if will require power/effort to insert in the slot with the jacket and now you phone wont recognize original nano sim in future). Overall 8.5/10
LG G Pro 2 --> build quality better than note 3, screen is subjected to likings of ips or amoled, sunlight legibilty is lesse than note 3, cam is ok , sound is good but downside is bigger phone, no s pen and no accessories in pakistan yet. Overall 7/10
Xperia Z2 --> excellent cam as Z1, large screen to phone ratio, ok loudspeaker output but cam heating the glass is risky and may break in winter if you put it on cold surface.No major update over Z1 as Z3 is also coming in September ( 6 month flagship cycle from sony) Overall 8/10
LG LG3 --> the most mature OS every by LG in their own phones, feel like samsung, Excellent screen to phone ratio ( smaller than Z2), good Cam , excellent speaker output sound and headphone sound. 2K display, personally feel snapdragon 805 should have been used with 3 gb ram but performance is no that bad, no lags on 3g ram version. Screen sunlight legibility is as good as lg phone we already have. Color are accurate that the best you get currently. Ideal screen size for 2K screen as 5.1 inch QHD will be overkill as seen on youtube with samsung s5, LTE-A. Overall 8.5/10