EXPENSIVE. Good seafood often is quite pricey, for example.
One of the reasons we stopped recommending this diet to our clients is the lack of quantifiable food options. It is very easy to overdo it with bread or olive oil, for example, and that will sabotage any weight loss efforts.
It includes wine, in standard Mediterranean form. Some people might dislike the idea of drinking alcohol.
Meal prep can be time consuming, for some.
Lack of structure is also a curse: it makes the weight loss yo-yo effect much more likely.
Not really a weight loss diet, is more of a lifestyle & culture thing.
The results are SLOOOW. Do not expect any overnight miracles!