@elisei Hi!
Well, there are the environmental and ethical advantages but I won't go into those since it's not the focus of your question.
The health advantages are quite big. Eating whole plant foods plant is linked with lower risk of all the major western killers (diabetes, heart disease, etc) and with lower body fat percentage.
Whole plant foods are very nutrient dense while being relatively low in calories. In my personal experience it makes it easier to control my weight without controlling caloric intake. Specially since I am on the low fat end of the spectrum. Meaning, as long as I'm eating whole plants I can eat how much I want, whenever I want. Due to the high fiber content, it's difficult to overeat.
The downside to this diet is the initial research that needs to be done. Learning what to eat and new recipes can be daunting at first but with perseverance you can make it