I currently have no problems with my LEAF. Its range meets my daily needs. As to how well the car (and battery) hold up over time, I shall see. The weather here in Philadephia is not too hot and not too cold, and so hopefully I won't have to deal with the problems caused by extreme heat or cold. The main thing which would occasionally help me is a better built-out public charging infrastructure. Right now, my house and a couple other spots are the only charging points I can absolutely count on, for anything else I have to have a backup plan. This is unacceptable to the masses, who count on the fact that there are gas stations everywhere.
While the LEAF is not perfect, it (the car itself) is very usable. What makes it unusable to most people is the poor development of the public charging infrastructure (compared to the development of the infrastucture for gasoline vehicles). Nissan needs to understand this; LEAF dealers need to understand it, so they can target the right kind of customer. I think, at least, someone at Nissan understood this at the beginning. I remember seeing this pie chart with three equal sized pieces representing the car, battery technology, and the charging infrastructure, and the text which accompanied the chart said that properly advanced technology for all 3 pieces were necessary for the EV to succeed. I'd say Nissan has been very successful at the car piece of the puzzle, moderately successful at the battery piece, but not very successful at the charging infrastucture piece. To be fair, Nissan doesn't have to build the gas stations for it gasoline cars, and they tried to do a good thing by putting in "public" charging points at their dealerships as a stopgap measure to help kickstart the EV revolution. But the problem with these dealership charge points is that they cannot be relied on in the way one can rely on a gas station. From dealers who plain refused to let drivers use them, to business hours only (somewhat restrictive in this era of high availability of 24-hour gas stations), to "call ahead" (come on, when was the last time you called ahead to a gas station), availability of these charge points just did not work out as they should have.
My point is, and this is coming from someone who has driving the LEAF as an only car for over 10 months and almost 11K miles, the car is not the problem, so Nissan, IMHO, you don't need to waste time trying to fix the design of the car. I love it the way it is. Although the battery is somewhat of an unknown at this point, and there have been some reported problems (although none for me so far), I still don't think its the largest problem. It is worthy of continued improvement, so if you're going to make changes to the car, improving the battery is where I think you could get the most "bang for the buck".
Now to the biggest problem: the charging infrastructure, or lack thereof. I see breaking into a few catagories:
1. The sheer magnitude of the required infrastrcture. In the past year and a half, here in Philly, we've gone from a single L2 public charge point to hundreds. But this is a drop in the bucket compared to the 10s of thousands to maybe millions that will be required. Right now there are zero quick-charge, they need to become as numerous as gas stations currently are.
2. The LEAF needs to intellegently support whatever infrastructure is deployed. So this may require minor desgin changes to the car.
a) Right now a 6.6KW on-board charger is a big thing because of scarcity of public charge points and the desire to pick up public charge as quickly as possible. Another driving factor for 6.6KW is current time-based pricing models. While it seems that they might eventually migrate to a kWh-based model, maybe not, since in the tradeoff the value of the parking space, which is traditionally charged by time, may be quite high compared to the value of the electricity consumed given that the circuit is limited to 30A/240V.
b) Then there's the issue of connector standards. Be it SAE vs Chademo vs Tesla supercharger at the quick charge level or J1772 vs Tesla vs having-to-have-the-EVSE-brick for L1 (in USA) or L2 (European "commando"), there ultimately needs to be some resolution. How Nissan deals with this, while it probably won't have long term consequences, it might if important events occur close to one or more tipping points.
So, IMHO, it is charging infrastrcuture piece of the puzzle that is what "got away" from Nissan's original plans. They originally recognized the importance of it, but given the nature of the task, and given that their resources were already consumed by the other to pieces of the EV pie, Nissan counted on AeroVironment and Ecotality (and others) to handle that piece. I think we, and probably Nissan, too, are disappointed in the way AeroVironment and Ecotality fulfilled, or failed to fulfill, this role.