TBoGT isn't a game you play for a great story, if you do, you are doing it wrong.
Well, the story in TBoGT is no masterpiece, most of the characters are just pricks There are some diamonds in the rough though like Gay Tony and Yusuf. Luis is also not a terrible protagonist, sure he doesn't have depth but his job was to just really finish off the trinity and he does it very well.
The gameplay department in TBoGT is just superb. For starters, the game no longer has a "filter" of any sort, making the game look absolutely gorgeous on any platform. Then there's the addition of nightclubs which is probably the best thing about the game. Not only did they add more interiors to the game, they also added new mini games such as champagne battles, club management, drinking and dancing mini games. They are not spectacular but I like to just chill out at the Maissonette from time to time.
The fun doesn't stop there. Once you get far enough in the game, you'll unlock the fun stuff such as tanks and parchutes. It's so much fun spawning an APC on the top of Rotterdam tower and driving off from the top of the building. The new weapons and vehicles are also fantastic. Now, you can create huge traffic jams and stick sticky bombs to cars. So much fun!
The missions in TBoGT are really good. They are quite linear but you won't mind that as they are just so fun and varied. The ability to replay missions was also sweet. The side activities round of TBoGT nicely, drug wars, triathlons and stuff were all good fun and I preferred them to IV's repetitive side activities.
In short: TBoGT is a fantastic game. It's just so fun to dick around with the new weapons and vehicles. I still prefer the vanilla game (mainly due to the atmosphere and story) but I do prefer TBoGT to TLaD. Gameplay wise, it's the best in the trinity IMO.