I have zero concerns about the long term durability of the Frontier, especially since I treat my vehicles well and do my own oil changes. I can't vouch for the rest of the Nissan lineup, but the Frontier is good to go.
The Pro-4X is the only model I even test-drove, so I can't speak for the ride or handling of the base models. I absolutely love the suspension, and it can handle any normal off-roading that you encounter. I've never done any true rock climbing with it, but it tackles all the shitty forest service roads without a hiccup.
As for parking, the problem is both size and maneuvering. It's a big truck, and doesn't turn well. It fits just fine in a standard size parking space, but maneuvering into the space can be problematic at times. I don't normally have problems in a regular parking lot, but parking garages can be a real hassle. I also gave up completely on trying to parallel park it. It can suck trying to take it downtown and deal with the limited and tight parking. As for width, it is not as wide as a fullsize, but it is much wider than the previous generation or a compact truck, but like I said it will fit in a normal parking space just fine.