[AT&T, Rogers HTC One X, Telstra One XL] greyhulk:
I purchased a Galaxy Nexus just a few weeks ago from Google and was loving it. Other than a few minor gripes here and there, I had no major issue with the phone and wasn't looking to replace it.

After seeing the One X reviews and how highly it was praised, I really didn't feel like I had a choice. My fate was sealed.

Having both phones in my possession, I'm going to list what I feel are benefits of the One X over the Galaxy Nexus, mostly related to software and the Sense Enhancements. I'll also list a few cons, because nothing is perfect.

Pros

Twitter contacts actually sync - This has been broken on all of my other Android phones to date. Sense is able to make it work and I really missed it.

Smartdialer - I use this feature a lot and stock Android doesn't have it.

Brighter Screen - On almost 60% brightness, my Nexus looked okay to me, but on about 40%, the One X is actually brighter.

Mail Sorting - Love that you can create sort tabs (such as unread) in the Mail client on the One X.

Camera Enhancements - I could go on and on for days on this one. I'll just briefly mention burst being built-in, rather than a seprate app or setting (awesome feature), quick access to scenes, and quick access to the flash. Also, having the camera and video buttons on the same screen is something that should have been done long ago. The toggle is old news.

Keyboard - It seems like everyone who reviewed the One X hated the keyboard. I was expecting to replace it right away. I actually find that I like it. Am I the only one?

People - I love the contact integration. On the Nexus, you only have Google + fully integrated. On Sense, you get Twitter and Facebook feeds as well as albums. It's how it should be on all phones, in my opinion.

Screen - All of the reviews on the screen are what sold me on this device. I thought the Galaxy Nexus looked really good, but the reviewers were right: There's no comparison to this screen. iPhone might have slightly higher pixel density, but that's on a screen over an inch smaller. The brightness and clarity on this screen is amazing and I no longer fear white backgrounds and light wallpapers (battery life).

Cons

Slower Exchange Mail - I can't quite put my finger on it, but my mail is coming in slower on my activesync accounts. Smart sync is off on those accounts and yet, I get e-mails on my iPad and Galaxy Nexus almost a minute faster, in some cases. It is a negligable delay, but a con for me, nonetheless.

Front Camera Toggle - This was actually something I used quite regularly and now it's buried, instead of quickly accessible. I think I would have rather had this than the button for effects.

Camera nipple - The One X is such a beautiful device. I would love to use it without a case, but I feel like if I do, I'll scratch the camera lense, or at least the ring, eventually. I wish it didn't protrude so far. I'm going to get a case to even it out.

Updates - HTC has actually been pretty fast with updates, but I still have a feeling that it will be 4-6 months after the Nexus gets Jellybean before we see it on this phone. Still, the software enhancements of Sense compensate for that somewhat.

Multitasking - The multitasking on the One X is beautiful, but it's form over function. On stock ICS, you can see all of the open apps and quickly scroll through them and dismiss them, Sense went with the full screen, card-like WebOS approach and now we can only look at one at a time. It makes looking for that open app a little more tedious.

That's my list so far. Loving my One X and the Cons in no way discourage me from keeping this phone. This really is the best android phone I have ever owned and I have had quite a few. Battery life is still up in the air. I haven't had it long enough to really test, but my Nexus was giving me a full day with 50% when I plugged it in. Based on reviews, I'm expecting even better with the One X.

I would be interested to see your pros and cons and what you agree/disagree with me on my lists.