I got the Moto X a month ago from AT&T. I went to the store and was choosing between the Moto X and the S4. In terms of performance, I did not notice a difference between the two in terms of web surfing, Youtube, etc. I did like the smaller size of the Moto X. My work gives me a discount so I got $60 off the price of the phone which basically put in a price range that I think most people felt was more suitable.
I also got the phone in like two days or so. Much faster than the original quote. When I ordered the phone via Motorola's custom thingamijgger, it did say that they had a phone in the configuration I wanted so that may explain the promptness of delivery.
Usagewise, it's been great. I only recharge the phone nightly. The other day was when I almost ran out of power before I plugged it in. I use it to listen to podcasts in the morning on Youtube, used it for various Wifi data stuff, used it for GPS to drive into downtown and then my doctor's appointment ran very late so I spent a couple hours browsing Reddit and stuff.
Speed is good, I haven't ran into anything that made me feel like I would regret it over the S4 and I don't see any reason why the experience will change in a couple of years.
The voice feature is nice for GPS because then I can just say an address instead of typing it out. It does save time then. It integrates a lot with your Google account. For example, I will search up the directions to get somewhere on the internet using Google. If I pick up my phone then it will automatically have the same trip. It will say how long it will take and with a press of my finger bring it up on GPS. So that's nice.
The notifications work well. It tells you what app has sent the notification and if it is an e-mail I can see the subject. I generally can tell with certainty about whether or not I want to wake up my phone.
I have only two complaints. The first is that the AT&T network is rather slow in my area despite being 4G LTE. It took me a half hour the other day on 4G to send a 10 MB email in gmail. The second is that sometimes it takes a while for the GPS to get situated which is annoying when I want to get going. This may just be the fault of the network though.