Ricotta gives a lighter texture to this cheesecake type dessert - which makes it even yummier because you can eat more! I sometimes serve it with baked figs, pinenuts and honey, or simply with a fruit sauce - in this case it's with raspberries. It really is scrummy!
I use frozen berries for sauces because they are generally cheaper and have a good flavour. If you want to use fresh berries then by all means do so.