Is the maxi cosi car seat good for the baby to sleep in?

my baby is nearly 3 months old and i always put him in the maxi cosi.. i took the part that holds his head etc off and during the night he sleeps from like 12 till 8 30 in d morning. his cot is quite big for him and whenever i put him in there he wakes up every 3 to 4 hours. i think he is more comfy in d maxi cosi..although a woman had told me not to leave him more than 3 hours in it while another one told me she used to put her granddaughter in it cos she used to be so comfy. what do u suggest?