Hi Antheia,
The one I've got is a really nice lightweight cotton and reversible (black on one side and patterned on the other) but from what I remember you can get canvas and polarfleece ones too. I think maybe in cradle carry style they might be a bit hot for summer, with bubs snuggled up so close to your skin, but kangaroo and hip carry would be alright with the cotton ones.
The other problem I had with them was the sizing- they are all one pice with no adjustable bits so you have to make sure you get the right size... but the baby store let me try a few on to be sure...