Yes, all of the service issues of an ICE apply to an i3 REx. But, since most people don't run the thing all that often, that can be both good and bad. Good in that you don't put all that many hours on the thing. Bad in that one of the issues people tend to have seems to be triggered by moisture getting into places it shouldn't. For those that use theirs more often, that probably gets burned off and won't accumulate. The other thing on the REx engine is that it's only two cylinders, so when you do need to do something to it, at least you're only dealing with two where it could be eight or more on some others.
BMW is pretty adamant about flushing the brake system at 24-month intervals, most everything else is simple checks that don't require much of anything else to be done. On the REx, even with minimal usage, you should change the oil annually if you don't hit the mileage requirement. The other things like wipers, cabin filters, brakes, tires, are all pretty much the same except on the REx, you're carrying around an extra 300+ pounds of weight all of the time...that will affect both the tire life, performance, and your efficiency.
2011 535i x-drive GT, 2014 i3 BEV
Soon (hopefully!) A 2021 X5 45e will replace the above