The dispersion of water coming out of the brass dispersion disk (diffuser) is pretty good even if not perfect.

But when I add the shower screen, the dispersion pattern doesn't look like a shower anymore but more like a regular faucet.

I have the ground coffee disk and filter like this:

Nuova Simonelli Oscar - is this diffuser for pods or grounds? [photo]

I really don't get that douche effect like this:

It's largely irrelevant. The open flow is several times that on a shot.. The shot flow is a hydraulic press, not a garden hose.

How is your espresso tasting?

Taste is good, but since I just bought this used machine I want to make sure all is ok.