Tis app (tomtom app v1.29) work on iphoneX v11.0.1
My iPhone X works equally well with both the old TomTom v1.29 (I have the US-Canada maps) and the new Go Mobile app (v1.9.2).
I hadn't downloaded the Go app until I got the new iPhone X because of all the concerns raised, so I only have four days of experience with it. I really do need the live traffic, otherwise I would have kept the older app without "upgrading". I have been pleasantly surprised at how well the Go app is performing. I haven't noticed any lagging yet. In any event, I am keeping both apps on my phone and will be crosschecking them in the days ahead. I am a long-time TomTom user, and was a Beta tester for them when they first entered the US market with the Pocket PC app. I use Apple Maps and Google Maps and others on occasion, but still keep coming back to TomTom as my primary navigation app.