I personally have NOT experienced any issues at all - mechanical or infotainment, and I have 3300+ combined miles on two different I-Paces thus far (1700 in mine and 1600 on a loaner - and using a loaner (FE just like mine) only because dealer has taken 3-4 weeks to implement some bodyshop work I wanted (paint license plate area and blackout the grill ring post-purchase), NOT due to any mechanical issues). This US forum is a very small sample size, with only a handful of regular participants, and (as you noted) tends to attract more complaints than useful posts, especially most recently. I've picked up quite a bit of excellent info on this forum, but if the negativity continues to overcome the utility, I'll likely opt out.
It is true that OTA has not yet been implemented, but not a big concern - probably just JLR being overly cautious as the car has been out in the US only 4 months and, unlike Tesla, JLR is NOT a cutting edge high tech/software company. I'm getting software updates (S18D infotainment as well as telematics and battery management (100kW max charge rate)) when I get mine back (this week). I think if the blackouts and other issues were as prevalent as you might conclude from reading this forum, there would be far more negative press about it, especially in Europe where they've sold 10 times as many I-Paces.
In the meantime consider this: the I-Pace appears to have won more awards
worldwide in its first year than just about any car in modern history. Overpriced (hence recent price cuts and 0% financing) and Underserved by Dealers (most seem to struggle)??? Yes, perhaps, but the I-Pace is still an incredible feat of EV engineering and design... and one of 3 finalists for 2019 World Car of the Year
. I think COTY will come down to the e-Tron and I-Pace, and the latter is a ground-up EV design vs. Audi's (meh) EV overlay on an existing Q3/Q5 design. I do think e-Tron will outsell the I-Pace (better marketing), but if you want popularity go with Tesla. I think Jag owners prefer singularity.