I tried to do as much research as I could before buying my Xterra. The only two complaints that I saw were 1) The interior was too basic and 2) The gas milage was a little low.
As far as the first complaint, I think that if you are looking at an Xterra you are looking at a work horse not a grocery getter. It may be simple interior, but it gets the job done with flying colors!!
And as for the second complaint, sure the Xterra doesnt get as good as many small SUV's, but I would chalenge you to try and take most SUV's to the same places you can take an Xterra. As for myself, I was driving a Chevy 2500HD before I got my Xterra, so my average fuel economy doubled overnight.
I love my Xterra and for the first time ever I feel like I bought a new vehicle that was actually worth the money.