Had this phone for nearly three weeks now - recently upgraded from HTC Desire HD.
Pros:
Screen is exceptional - Super LCD2 is huge improvement upon Super LCD1. Rich colours and great high def screen.
Beats audio sounds fantastic. You do need to get a good set of headphones though, the ones which come with the phones aren't great.
Camera is very good - hold the shutter button down and it'll take loads of shots in a very small amount of time. Even gives you option to accept phone's suggestion of best pic and delete rest (or you can keep all) - good for gigs and fast moving objects.
1080p video recording is very nice, plus you can take still photos whilst recording a video.
Very fast phone - menus, web browsing, game loading etc.
Nice and slim - feels solid and durable, with a nice finish.
HTC Sense overlay - still so much more intuitive and nicer to use than iOS or touchwiz.
Cons
Battery really isn't good. We all know that smartphones have low battery lives, but this one really is bad. Worse than my 19 month old Desire HD! Am aware of tips for saving battery life - keep WiFi/Internet off, dim screen etc, but still lasts just under a day with moderate useage. Such a pity - the mp3 player is so good, but I daren't use it for more than an hour on a long train journey.
Push email does not work. I'm pretty tech savvy and have adjusted the push/sync settings correctly, but it simply won't push my hotmail emails to my phone - I have to go in and check manually . Tried unsyncing my hotmail account and resyncing it, but to no avail. I've found a way around this by downloading the official hotmail app, which works fine, so I get my emails pushed that way. Shouldn't have to have done this though. Didn't need to with Desire HD, push worked perfectly fine on that. Not sure if this is a Sense 4.0 issue or Ice Cream Sandwich issue? This is the 2nd One X that I'm aware of which has this problem. The One S wins outright on the battery life front - my friend getst just under two days on one charge with moderate useage.