There’s two questions here. Let’s look at them separately.
1) Is green tea any good?
Yes, it is. It’s quite mild compared to black tea, so even if you “don’t like tea” it’s worth a punt; as a comparison, it’s like avoiding lager because you don’t like guinness. Lemon tea tastes of lemon, not tea.
2) Will it prevent cancer, help you live longer, make your kids go to college and stop the milk in your fridge from going off?
Of course it won’t. Most (all?) of the wild claims on that page are unproven at best. If there was any truth at all in it, you wouldn’t have to ask on here because we’d all be doing it. If you want an unbiased opinion you need to look somewhere that isn’t trying to sell you expensive vitamin supplements.
If you want to improve your health, I’d suggest a balanced diet and more exercise, rather than wasting your money on woo-peddlers.