I bought my 2014 right after they became available. WOrks fine. It only has about 13K miles on it, when I get home, it gets plugged in, and sits there. The estimated range is still in the 80-mile range. It was cooler a couple of days ago, the car said 69-miles when I got in then I drove 14-miles, and it said 71...the estimation is not always correct, but you get a feel for it and where you'll be driving after awhile. Normally, I don't need more than about 35-40 miles. If I'm going to be going much further, I take my ICE. I might stretch it out to an anticipated 70-miles if it won't be high speed highway miles. It's not let me down yet. Drives like new, looks like new, expect it to last a number of additional years, so I am not worrying about depreciation. If it continues along as it has, I could own this thing for more than 10-years. I don't NEED a bigger battery. By then, there will be lots of options, but unless it starts to give me grief on service issues, I'll just keep it. If it were a REx, the additional maintenance and complexity, I'd probably have not bought it and opted for a different hybrid.
Seriously consider how much range you need and how often, plus, if you have an alternative. That can make the decision on a BEV verses the REx easier. I opted for the more efficient, lighter, simpler BEV, but your needs may differ both functionally and financially. Adding 10% more to the vehicle weight has it's detrimental effects if you don't need it.
2011 535i x-drive GT, 2014 i3 BEV