I have a 2005 Tacoma 4WD TRD V6 with manual trans.
First of all, I love my truck. Unlike a previous poster, I really like the new look of the Tacomas and like how roomy it is inside. I would certainly buy my truck again, but I might go for the automatic instead of the manual. Don't get me wrong, I love driving manual, but this manual has long throws, has a decent amount of feedback from the road, and is not smooth like I would like it. The auto is rather good in the Tacomas...and gets better gas mileage on the highway because of higher gearing. Of course, we are talking about a truck here, so I really don't mind the manual...just the auto is certainly more refinded.
I do love the ruggedness of the truck...I've driven it in all kinds of off road terrains. It is not as good as the last model (which was taller and narrower) for offroading...but it is still dang good. I've never had any issues with the truck...everything works like it did the day I bought it and I expect to keep it another 10+ years. I've already got 40K miles on it and maintenance has been simple (oil/filter, air filter, trans oil, etc). The powertrain is rock solid.
The truck is a bit pricey...you certainly can get a similar equipped (or even nicer) Frontier for less money. It gets a little worse gas mileage, but is cheaper to begin with. The engine is slightly more powerful, but the truck is a good bit heavier, so the Tacoma wins speed wise. The Frontier as a little nicer ride than my TRD off road suspension...but in the ruff, the TRD suspension shines.
As far as gas mileage goes, I generally get ~18MPG with mostly city driving. On trips I get around 20-21MPG as long as I keep the speed at 70MPH. If you get the Auto, you should get even better gas mileage.