Take it from a truck guy!

I bought a 2002 Frontier Crew Cab XE 4 months ago. It had 46,000 miles on it when purchased. In that time I have put just a shade over 10,000 miles on it. With about 1,000 of that pulling a trailer with a small car on it.

POWER....

I must say it is not one of the most powerful trucks I have ever driven. I can also state my 1982 Nissan 720 pickup with a 2.2 liter engine with 370,000 miles on it will almost keep up with it. Both unloaded of course. The Frontier shines when I attached the trailer with a Sentra on it though. I live in the foothills of the Ozarks in Arkansas. Not extreme mountains but enough to get a loaded trucks attention. The truck has a fair amount of torque. That is what is needed when hauling a load. It didn't wheeze too much when pulling although (thankfully) it has a manual 5 speed which let me choose the optimal gearing for the situations. I have a sneaky feeling the automatic would pull the breath out of the 3.3 V-6.
Unloaded it runs so-so. Very smooth transfer of what power it has. You'd be in no danger whatsoever of trying to race it. Just about any grocery getter will outrun it. It does seem to pull better once you're above 3,000 RPM's.

ERGONOMICS....

I believe this is the most comfortable truck I have ever driven. Heck, maybe even one of the most comfortable vehicles. The seats are supportive without being harsh on long drives. My 3 preteens have room to spare in the back seat. I have read some do not like the instrument layout. I happen not to be of that opinion. It is smart without lots of bells and whistles. An oil pressure and volt gauge would ease my mind alot though. Never been a fan of "idiot" lights. The steering wheel has the cruise control buttons on the right side. Just my little quirk but I would have preferred them on the left side. The suspension is a little stiff when empty but when loaded it has a perfect ride. I like the stance of the truck. It has a comfortable height. Mine is a 2WD but I am CONSTANTLY asked if it is 4WD.

GRIPES....

My number one complaint...21 mpg. I would think with no more power than the engine produces it should scare 30 mpg. I have done everything I know how to do yet 21.8 was the highest achieved. 19.4 while pulling the trailer. Not too shabby there in my opinion.
The wisdom of Nissan designers escaped me when I noticed it didn't have ash trays. Although, not a smoker I do have a tendency to collect change and the ash tray for me becomes a change tray. I miss that.
Lastly, the ABS seems to be a little too functional. When stopping on a downhill grade and the road is washboarded the stopping distance is increased. I don't care what Nissan says. It almost makes you think you're not going to get stopped in time.

OVERALL...

Due to Nissan's legendary reliability (note above...370,000 miles on a 1982 model with just basic, routine maintenance) I believe this truck should last for years also. The V-6 is the basic design Nissan has had since 1984 so the bugs should be worked out by now. There is a slight whine in the transmission at highway unloaded speeds. The dealer says it's normal. I tend to agree since I have driven others that have the same noise. I am skiddish about the plastic fender flares though. UV rays tend to be harsh on plastic. Time will tell.
The only mechanical problem I have had with the truck is the tailgate lock. Sometimes it locks on it's own. Sometimes it doesn't. I just make sure if I need to open the tailgate I have my key with me.
Nissan has shined with this truck (although it favors the Ford Explorer SUT a little more than I like since I wouldn't own a Ford if they were giving them away).
I highly recommend this truck to anyone needing an SUT. Comfortable. Reliable. Fun to drive.