Alright, I stopped by the Taco Bell in the OP and tried regular Seasoned Fries for a baseline of how they tasted, and also the Supreme option to see how they tasted in a more complex dish.
First off, the Seasoned Fries:
They reminded me of Carl's Jr/Hardee's fries in size and texture with a little more crunch to them. The fries themselves were pretty average, but it was the seasoning that put them over the top. The seasoning was pretty good, it tasted like a non-spicy Cajun seasoning. These are mid-tier fries with a good seasoning on top. (For reference I consider Del Taco fries to be the highest-tier fast food fries, and these Taco Bell fries don't come close to touching them).
Now on to the Supreme Fries:
The toppings were pretty bland, they work much better on nachos and make for a sub-par serving of chili fries (if that's what they're even going for, because they sure aren't carne asada fries). The thing that saves this from just being depressing, and makes it more of an "alright, if I'm ready at Taco Bell and in the mood for it" item is, again, the seasoning. The toppings are bland enough that you taste the seasoning through all of them. Also the prongs on the sporks they had felt slightly too short for the thickness of the fries, making it feel kind of awkward to eat.
So really, for both items, it's the seasoning that's good, not the food.