main points:
altho nexus was produced by different manufacturers, google is deeply participated in the process and thus the high expectations.
n4 was one of the biggest surprise in 2012 in US. (low price, beast hardware, nexus series)

HARDWARE:-
5:3 screen looks wider than 16:9 and more suitable for mobile
no extra buttons / etc in front design of n4 and thus it looks clean (one piece).
the curved design makes n4 looks 3d-ish
the back panel is one of the main selling point of the design (simplicity yet attractive)
the nexus branding instead of Google's branding.
however looking at hardware / overall look is not enough to evaluate a phone. need to evaluate its functional, durability and creativity
nexus 4's durability is not good enough (thin glasses, the side rubbers could not provide enough protection/damage mitigation from drop).
nexus 4 is not the only phone which uses glass panel in their body design. my previous iphone 4s had been dropped multiple times (naked) but there are no issues of glass cracking
and thus, if comparing nexus 4 with other phones via drop text; nexus 4's durability is a big lose here.
it's sad if we have to "put on" a casing on such a nice design phone, just to protect it.
nexus 4 is not a perfect design but is more like a good / beautiful vase which it's worth to purchase it again even after it breaks

DISPLAY:
nexus 4 uses IPS from LG instead of OLED from Samsung
nexus 4 is much brighter than previous model
nexus 4's colour looks much more natural as compared with galaxy nexus
however when compared with iphone 5, there are slight offs in colour when compared with real-world-colour (based on colour board)
it's dissapointing as both displays are made by LG (for iP5 and N4)
n4's naked screen is very smooth, it's sad that we have to apply screen protector on it.
nexus 4's 5:3 ratio have a clear advantage over 16:9 of ip5 (better browsing experience, photo viewing etc).
although n4 have some slight improvements and downs as compared with previous model / ip5, it's still a good display

OPERATING SYSTEM:
n4's main selling point is the OS
from first version till ICS (4.0), google keeps on adding stuff (addition)
after 4.0, google starts to do reduction (simplicity of logical processing[??] and operating methods)
logical processing: one of the example is the removal of "MENU" button and make it visible in the app itself; or the changing o typing method (shows in notification bar instead of long-press-hold)
operating method: e.g. long press of desktop can only change wallpaper now. widgets are now in app drawer (removal of non-important functions to other places and reorganize)
another major change is the virtual button (non capative / physical button) and fixing the order of buttons (instead of allowing manufacturers to put them as they wish).
and thus, the manufactures do not have to worry about "these buttons" anymore and can focus on increasing the screen size / etc)
one of the main successful feature in 4.2 is the friendly hand gestures (see new camera app, where settings can easily be changed using a finger instead of accessing the menu far away in other place. one bad example is iphone's "back" button which are usually allocated on top-left which are hard to access (have to move hand etc))
allows lockscreen to have similar functions/widgets like desktop, simplifying overall steps needed to access certain information/apps (e.g. messaging). eliminating the need of unlocking > click app > enter app from directly entering to app @ lockscreen
the main differences between google vanila ROM versus manufacturer-based roms is where manufacturer will 'add stuff' on top of vanilla android and thus, they cannt update as fast as google does (because updates are really fast)
manufacturers also hard to keep up with new standards set by google (e.g. the button placement, elimination of "MENU" button, etc).
the difference between IOS and Android's OS (example given by him):
Android = plant a big tree from a seed, repair and cut the leaves to make it beautiful
IOS = chop a tree to its simplest state, and slowly adding new "branches" or "leaves" and thus IOS's base operation are still the same until now (using simplest operation: open app, back, open app, back)

summary: after changes are made, android system is much more matured now, however there may be disadvantages in these "reduction" (simplicity) as well. such as lock screen is much more similar to homescrene concept now, which increases difficulty in understanding by user; and thus increasing the learning curve of user
the new "on screen button" is not really standardised now, not everyone accept it such as gamers (the button is blocking the screen, etc). maybe webOS can give us some hint from there

i believe most of the smartphone nowadays are very "powerful" enough (in terms of specs, fps, gaming fps, etc). not a big noticable differences.

next is the webpage loading speed. there should not be differences in loading, however nexus 4 loads blazingly fast with Chrome and we even initially thought that we did not clear the cache. However after conducting the test multiple times, we are sure that the n4 does load faster than ip5. However, the ip5's zooming feature is much more smoother as compared with android's

CAMERA:
main point: N4's white balance is very terrible, colour always off-balance (such as more to red, more to green, more to blue, etc) as compared with IP5
the colour temperature is more "cold"
green not enough green, more to yellow-ish, etc.
low light condition = very terrible white balance in n4
however the biggest problem is the light reflection during day/night
light filtering is not good enough
caused by various factors which involves both software & hardware
main cause by the limiting budget (i guess he meant the price set @ google store)
front camera is terrible and lots of noise
n4's main advantages is more on OS side than hardware side (main specifications apart)

BATTERY & THERMAL PERFORMANCE:
both use same setting and conducted within 5 hours of continous test (gaming, browsing, listening, etc)
refer to video from 18;30
the comparison starts from GAMING, MUSIC PLAYBACK, LOCAL VIDEO PLAYBACK, E-BOOK, WEIBO(facebook alike?), ON-CALL, WEB BROWSHING, CAMERA, REMAINING BATTERY (total of 9 tests from top-to-bottom, left-to-right)
N4's battery consumption on different activities are much more balanced consumption as compared with IP5 which have obvious diffeernces in 3G (weibo) consumption.
as for temperature... just look at the graph and pictures... (back temperature, front temperature)

PHONE CALL TEST:
watch and listen the video... mainly about noise canceling etc...

CONCLUSION: (oh finally...)
LG gains the most benefit from this (the right to produce Nexus 4). because samsung is the only manuf which are leading the android market.
LG's product hardly attract customers. and thus, this allows LG to focus on hardware (what they're good in) as google solves all the software-related issues as LG is not good in software-related area.
if u don't despise it as a fragile product, and loves pure vanilla google experience, nexus 4 is a good product for you.

blah blah blah..

PEACE!!