I came to the X from an iPhone 8. There were not really any negative things that I didn't expect after doing research and some lengthily play time with one in the store. There have been a few pleasant surprises though.
1. I really thought I would dislike faceID. I don't and it works better than expected. The bummer of playing with one is store is that you can't test out faceID.
2. I thought I was going to miss the home button and not like the gestures. After 3 days I now love the gestures and don't miss the home button one bit.
3. The notch does not bother me at all. Day one I noticed it every time I looked at the phone, days 2 less and day 3 on I hardly even notice it's there. I've also come to appreciate it as it's not a run of the mill looking phone.
My few gripes:
1. I wish I could have faceID unlock right to the home screen without having to swipe up
2. I wish I could close apps without having to hold before swiping them away.
The phone rocks, battery life for me has been stellar, faceID works well and I dig the gestures.
My sentiments exactly except I came from a 6S.