after 2 days of use on Miui 7, performance slightly but tangibly better n smoother n faster. standby time is almost as good as 6.6.10 (refer to my previous posting in this thread), which is very much better than my note 2, comparable to the most thrifty standby android phone out there (yes yes apple still the king on this i have to admit but we are talking about android)
now for the bad news, the faster n smoother does come at a price in terms of warming (notice i didnt use the word heat up) and slightly higher battery usage (again notice i didnt use the word drain), let me explain.
when installing many program at one go (when initial setting up the phone ) or when browsing esp on 4G or when the screen is tuned to 50% Auto brightness and on for prolonged period of time eg. ( > 5min), the phone did get warm, the temperature would be similar to when you quick charging (approx. 45- 49?), at 49 some may feel slight discomfort but is not overheating till like 60C ie burnt sensation. But frankly speaking is anyone (besides me hehe cos i am testing) not using a casing, which will protect from the temp? this is where MIUI 7 is better than 6, even at the warming, i didnt feel the CPU or GPU throttle, which i did feel when i am on 6.6.10 (balance mode). so kudos to XiaoMi, i think their concept is to spike the freq to complete the task and race to sleep.
it is also exactly becos of that, the battery usage increase significantly, as i unplugged at 530am (100%) when i woke up at 630am its 99% but as i start to use my whatsapp and surf the net in train, by the time 8am its down to 85% but once i off the screen on standby (its still on 4g with email / FB / Whatsapp coming in) it is very thrifty in only sipping very little battery. Hence thats why i said its is not draining, becos if its draining meaning even if you left it in standby mode it will continue to drain.
hence conclusion, 615 is slightly under powered and under efficient for a mid-high phone as Mi4i , so much that XM need to crank up the freq to 1.7Ghz and at its apex freq and use brute force race to sleep tactic, as we all know thats when the least power efficient ie. the heat and high battery usage. Though it solved the lagged and thermal throttling issue.
now is it worth to get the mi4i 32Gb? Yes and no. Yes is becos for the specs we are getting and the accessories we are getting (btw i gotten 2 charger 1 quick 2A charger and one normal 1A charger, 5" 1080 IPS, 2GB ram, 32Gb (usable 25.6Gb) and some neat features of MIUI 7.
No is because, though there is no issue with gap, the made quality of the phone is only slightly better than RedMi which is selling for 169 about 1/2 the price. the SOC they are using are slightly underpowered, though not their fault as they cant use 801 as that will eat into their high end flag ship, hence one step lower than 801 is 615 (as 800 is EOL). with this in consideration, XM could have and should have put a bigger battery inside. As no way they can solve the warming up issue (without increasing the Bill of Material ie price of the phone) as the phone is very thin and is not made up of metal for better heat dissipation.
here you go might 2 cents worth of review of Mi4i on Miui 7.