Thought I'd post my general thoughts having been driving the Navara D40 (V6 Outlaw) for around a year now. Overall I think Nissan have let themselves down badly with the Navara and while not every aspect I'd be critical of are shared between the D40 and NP300 too many seem to be from my limited experience of the new model. While there is a lot I like about the vehicle there are too many areas they've skimped to save pennies or got things just about "good enough" and let it at that which sabotage the overall, which should be very positive, impression. Whether that is stuff like the door rubber which ages far quicker than other vehicles unless regularly treated, the potential issues with chassis corrosion, etc., the steering which overall is very good but has some annoying vagueness at times which I'm sure they could have got right with a bit more effort, the ride is generally good with a decent feeling of being planted on the road when there is a bit of weight and/or a full tank of fuel involved but get down to like half a tank of fuel and it bounces around a ton and very different to how it feels with a full tank - again something I'm sure they could have improved on with a bit more effort (obviously there are limits in that context when it comes to pickups). Can't really comment on reliability as I've not had it long enough to get a good picture on that and 1-2 issues are related to the dealer I bought it from rather than the vehicle itself.
I've found it hugely capable off-road much more so even than it is usually credited with but on the other hand if you do actually use it properly it doesn't shrug off the kind of rough and tumble other pickups have no problem with and you will be replacing things like ball joints and/or having to do low key maintenance (that you wouldn't have to do as readily on other pickups) and as long as I keep the fuel tank topped up I find it pretty comfortable on the road especially with the leather seats and refinement of the engine on this model - little bit more cabin noise than I'd like but overall I'm pretty happy in terms of a place to be on journeys.
I do really miss having a proper boot though - while there are some under seat storage bins they aren't as big as on the US pickups I've experience of and on my vehicle the previous owner specced it with the top tier audio so has a massive sub-woofer taking up 2/3rds of that space.
Fuel economy hasn't been bad for me personally despite having the 3L V6 model - not hugely behind the kind of stuff I'd normally drive and largely it isn't a problem practicality wise on UK roads though I do find myself planning ahead when it comes to parking and tend to avoid narrow country lanes when I can (though living out in the sticks that isn't always possible).
Feel badly let down by the VW dealer (and not a small time one either) I bought it from - glad I didn't go in there and act on the impulse of spending new Amarok money - the work their service department did making it ready for sale has been done to a poor standard causing me more time and money down the line sorting (mostly stuff like panels only put back with 1-2 out of the 3-4 screws that should hold them in place and stuff like that but there are a couple of areas where they did work relevant to the running of the vehicle where things weren't correctly tightened up as well), they incorrectly told me it had already had a chassis inspection done which formed part of my purchasing decision and I've found out subsequently from Nissan to be untrue and the tyres put on it for sale were incorrect spec for the vehicle causing me more cost and hassle down the line (also different from those in the ad and I'm 99% sure but can't be certain were on it when I agreed the purchase). On the other hand the nearby Nissan dealer have been excellent and done a lot to help out with the issues which makes me a little more likely to consider the Navara again in the future plus I do like the Navara shape - while the Amarok edges it on looks I prefer the rounded off wheel arches on the Navara to the squared ones on the Amarok.
I'm undecided on the future - there is a lot I like about owning a pickup just the feeling of almost being ready for anything, etc. like being a bit higher up when driving but when I bought it my usage was a little bit of everything so a pickup was a good compromise as it was at least OK or better at everything but at the moment my main usage seems to be pounding A roads so I'm likely to be reconsidering my options I do miss having a consistently good ride quality as well. If I did go pickup again I think on balance it would probably be the Amarok, none the less I wouldn't be in a hurry to buy a pickup that didn't have a V6 engine which is currently lacking in the Navara range, but with my usage I struggle to justify Amarok money versus the other vehicles that price range opens up. (I'd also have to go further afield VW wise as I definitely wouldn't go back to the main commercial dealer for this region).
EDIT: Also something about this Navara I really click with - the general layout of things, the engine response with the V6/computer/gearbox, etc. just work for me which doubly makes me sad Nissan didn't make a bit more effort.