I traded a 2010 Tundra for a 2020 Tacoma and for the most part haven't regretted it. There are certain places the Taco can go that the Tundra couldn't make, and the turning radius and ease of parking (in parking lots and in the garage) are major advantages. The Taco is definitely better on gas mileage, especially on the highway (on a flat surface I routinely get about 25 mpg at interstate highway speeds). It's still a bit of a dog on gas in town, but it is a Toyota so that's to be expected. The truck has been rock solid reliable approaching 100K miles.
That said, I do miss the interior volume of the Tundra. Our kiddo is double digits in age now, and the sports gear soaks up a lot of backseat space. Leg room is also starting to become a problem, especially if you put two full grown adults in the front. The front seating position for the 3rd generation is downright uncomfortable for anything other than a short drive unless you install something like Desert Does It seat jackers (those have been a life saver). The more car-like seating position really hasn't bothered me much, and the headroom is more than adequate for someone over 6ft. Plan to get a locking bed cover if you ever take a family trip in it as you'll run out of interior volume quickly. The only other drawbacks are the slightly reduced bed space, and the fact that you don't get as much respect on the road. Given it's about the size of your standard 3-person people hauler, folks won't be as apt to give you right of way. The 4th generation Taco is a noticeably larger truck though.
All-in-all, The Tacoma is a good truck and has met all of our needs, but I'll probably go back to a full size when it's time to get a new vehicle again. We've all but outgrown it for the amount of traveling we do, and it's only getting tighter. I'm patiently waiting (hoping) for Toyota to work the kinks out of this generation of Tundra, so we can live with the Taco for a while longer.