I own a 2004 F150 FX4 (new body style), and it is my first Ford vehicle. The truck has been a tank through a few harsh Colorado winters and I haven't had one issue with reliability, although I'm only at 35,000 miles.
The comfort level of this truck is tremendous (stiff frame with welded-through crossbars, outboard rear shocks and independent front suspension makes it handle much like a car), yet it has taken all of the offroading I have put it through.
The 5.4L Triton pulls my 27' camper like a champ (it's no diesel, but it's got good torque), and there are many nice aftermarket products for this truck (programmers, CAI's, e-fans, drive by wire throttle bodies, exhausts, superchargers etc...). I'm looking forward to the rumored 379 cubic inch (6.2L) Ford Boss engine that might be in the '09 F150's.
Oh, I read someone say that they thought the interior was cheesy and looked like it is 'snapped together'; well actually, nothing could be further from the truth. The interior in my FX4 is very comfortable, practical, tough and good looking. In fact, I've never seen such a nice interior in a truck (except for the new redesigned Tundra)