No, its actually the opposite, and its not an overstatement. Mine was down to 65% capacity at 40,000 miles. That's about 50 miles of range, making the car rather unusable. Although they did release a newer chemistry in 2015/2016, which was supposed to be more heat resistant, it really wasn't much better. My replacement was already down 10% in <10,000 miles.
It has actually become even worse now that they have been trying to pack 30 kWh and more into the same space, creating even more heat. Hang out on MNL.com for a while, and you will get an idea of what an issue this is for people in hotter climates, and I think Las Vegas qualifies. IMO, a Leaf is only a bargain if:
1) you can get one USED, as they have HUGE depreciation, and
2) you get one that came from a northern, cooler climate.
Now, the 2019 Leaf, that might be a completely different beast, as they are supposed to be sourcing a pack from LG that has thermal management.