My wife and I were able to see the touring I-PACE prototype this past weekend, and were allowed to turn it on and play with the sound system, A/C, buttons, etc, but weren't able to drive it.
As someone who has a Tesla Model X, I can unequivocally say that the I-PACE is a lot smaller. I can seat seven in my Model X, but five is the most in the I-PACE, and that fifth person is not going to be happy. Leg room in the second row can be tight depending on the position of the front seats. Rear storage is flat in the I-PACE, whereas the Model X has a deep well underneath for additional items. The I-PACE's 2nd row does fold forward if necessary. Getting in and out of the I-PACE requires ducking, which the Model X does not.
Size aside, I found the I-PACE interior to be worlds more luxurious than the Model X. All controls were intuitive at first use (aside from the A/C dials, but once I understood how they worked, they made sense).
The I-PACE also looks a lot sexier on the outside, but that design does impact the coefficient of drag and efficiency of the I-PACE. (My Model X P90D gets about 250 miles fully charged, and the I-PACE is rated at 240 miles with the same size battery; but the I-PACE is a smaller, lower vehicle, so it should be well into the high 200s.)
A/C was robust, cooled front seats were nice (although I wasn't 100% convinced the seat back is cooled like the seat bottom), and the Meridian sound system was excellent. Maybe not Cadillac Panaray or Lexus Mark Levinson nice, but it's a quality system, and much better than Tesla's. However, no matter how hard he tried, the salesperson could not get the I-PACE to pull in the equivalent HD station of any local FM station, so I can't confirm whether the I-PACE has HD radio compatibility.
Some items the salesperson couldn't reconcile were whether the I-PACE gets Apple CarPlay and Android Auto (different answers depending on who you ask, and I couldn't find a definitive answer on Jaguar's website). But for sure the Model X doesn't have either. You can't even plug in an iPhone via USB and play it in a Tesla - it's all Bluetooth, which impacts the fidelity negatively. However, Teslas can play FLAC files natively off of a USB thumb drive, and the salesperson couldn't tell me if the Jaguar could.
Also, Jaguar doesn't appear to have an equivalent "Auto Pilot" system like Tesla. The salesperson was trying to tell me that Lane Keep Assist and Adaptive Cruise Control combined to offer the equivalent, and I laughed in his face. Mind you, the website videos on Jaguar talk about a "Steer Assist" feature that sounds more Auto Pilot-like, but there doesn't appear to be a way to order it, so it could be vaporware.
The I-PACE will have over-the-air software updates capability. Of course, so do newer Cadillacs, and I've yet to see a single OTA software update from them! (Cadillac is the worst when it comes to CUE infotainment updates.) So just because the I-PACE has it doesn't mean it'll get used.
That's all I've got for now. Hopefully Jaguar will call me to drive one soon so I can report back on that.