Htc 8x owner for a week. So far i hav to say im quite happy with my phone.
I dun usually do much with the phone besides calls, sms, watsapp communication during work, pictures and browsing. Dont game with the phone (pc for gaming only plz =P )

So far the experience have been great! the ui is simplistic and layout is straightforward. there's not much animation tbh (heck! the loading bar is just 5 small dots flashing horizontally thru the screen!), which may explain the butter-smooth response of the phone.

So far i'd not encounter one single lag on the phone, fb, youtube etc. there's some hick-ups once in a blue moon but i think thats more of a connection problem.

As for the cons.... well, the battery. so far it can last till nite time with moderate surfing and watsapp. (dey say it ll get better once the battery optimizes itself, so i ll just see. i do wish it could b longer.

And another thing... have u seen this gorgeous phone? (i had to admit i fell in love the first sight lol) so far lots of ppl r complementing on the design of the phone. its freaking thin and just sits rite in your palm.
BUUUTTTT, theres a drawback, it looks fragile. and frm the report i'd read ard the forums, the corners of the glass WILL CRACK if you not careful enough. I dropped my phone once from a 1 m tall table, luckily it landed on the backside of the phone. i wouldnt dare imagine what will happen if it landed on the glass side. PLUS id read about the colors on the corner of the phone faded/gets dirty easily.

Tldr,
pro: its simplistic ui, totally lag free, and most importantly, its gorgeous!
cons: its looks fragile, drop it n u ll cry. Corners getting dark, battery is on the low side.
Btw, id seen both htc 8x n lumia 920, hardware wise, 920 is def the better phone, but heck, love the 8x design so much i think the tradeoff is worth it.