I went from 7 to XS and have really enjoyed it. My 7 was in perfect condition as well. The main reason for upgrading for me was the camera and the ability to have my personal and work numbers on the same phone. Obviously I haven't been able to test out the second item yet, but the camera is fantastic as most here have already mentioned. The battery life on the XS is even better than what I remembered my 7 being when it was new. I had some problems with the ESPN app but gave up and deleted it and haven't had any battery problems since.
All of this is not to say that the 7 wasn't a fantastic phone, I would have probably been happy with it for another year or so. At the end of the day I had to reconcile the cost, new features from 7 to XS, and expected life of the XS. This phone is solid. I expect to have this phone for 3-4 years. It feels more future proofed than any other iPhone I've ever bought. I'd be interested to hear if any other readers agree with that feeling. Again, not to take away from the 7. It still is a fantastic phone. But I felt that moving up to the XS was money well spent and will continue to be for many years.
Obviously, the choice is yours as you'll use your phone differently than me. But I have really enjoyed the XS and do not regret the upgrade.
Let me know if you had any specific question and I'd be happy give my two cents.