On any EV, your actual range will vary by how you drive it, the terrain, and the temperature. My 2014's indicated range can vary over 30-miles summer to winter, not counting terrain or driving conditions.
When deciding what car to buy, you need a realistic idea of what your real need for range is. In my case, 95% of my needs are less than 20-miles/day, so even with being inefficient in the really cold, middle of a cold spell, I've still got more than enough.
The i3 will display the expected range to empty left. Just like on an ICE, that may or may not be accurate. It bases that calculation on what happened the last 18-miles that the car was driven. So, checking one out on a dealer's lot may be quite inaccurate based on real time, as it will likely have lots of cold starts (HVAC load), and people experimenting with it using full acceleration.
THere are some ways to get an approximation of the battery health, but that isn't perfect, either. The dealerships have a special procedure they run to determine the health of the battery. Supposedly takes about a day to perform. Right now, mine's indicating 46-miles, but, my brother-in-law had been driving it short hops with long delays between...worst case situation as it was quite cold when he was doing it. This time of year, I generally see a low of about 60, and in the summer, I've seen over 80-miles. It just depends. Since June 2014 when I bought it, it's dropped about 5-miles of range. Still, way more than my normal needs.
Your needs would depend a lot on when and where you can recharge, and how far you need it to go.
Some feel they must have the REx. My thought was why carry around that extra weight for something that may only get used once or twice a year and requires all of the maintenance hassles of an ICE: buying gasoline, engine oil, filter, muffler, etc. Yes, some people take theirs on long trips, but the hassle isn't worth it to me. If it was going to be your only car, you might want to consider borrowing an ICE for a longer trip or renting one. Everyone has their hassle limits, and to me, it isn't worth it. Not everyone is in the same situation...only you can decide.
FWIW, mine has been pretty reliable. I had an issue with the charge plug release, but that's the only real thing. They did have a service campaign on a few things to resolve some issues, but those never actually caused me an issue.
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)