Only good thing? More matches to see to bet, and surely more people in the cities who host the tournament.
More money too. Big nations like India, China and many others will bring new cash-flow to FIFA.
They are even considering 12 groups with 4 teams and another one is to divide tournament in half and then winners of each half play in final.
8 groups with 6 teams in each group will do the calculation easier. There will be more matches in the group stage though. Each team will play 5 matches where they are playing 3 matches in the current format.