Hi jolokster - check out the previous discussion on black tomatoes linked below - lots of discussion in it. IMO flavor/taste will depend on the variety itself, not the color. They all taste like tomatoes ;) but some varieties are much better than others.

Can't think of a black roma one off hand but there likely is one. I know there are some black plum ones and I have grown Black Pear.

Dave

Here is a link that might be useful: Favorite black tomatoes discussion

There is a variety called black plum, but it is more like a large cherry in that the ratio of seed gel to flesh is relatively high. Roma-sized tomatoes like Nyagaous and Black Prince are salad tomatoes and thus also have alot of gel. I don't know of any dry paste-type (like Roma) black tomatoes, maybe others do. From the blacks I know, if you want something meaty for making sauce Japanese Black Trifel, Brad's Black Heart, and the beefsteak types (cherokee purple, indian stripe, Carbon, Black from Tula et al.) would work better than say Black Krim (which is a little seedy) for sauce.

There is a distinctive earthy flavor to some of the blacks (Paul Robeson, Black Krim, Japanese Black Trifel, Nyagous...) which others such as Carbon, Black From Tula, Cherokee Purple et al,... seem to lack the trait, at least when I grow them.

Purple Russian. I know it says 'purple' in its name, but it's a black tomato. Oblong, Roma-shaped, great taste, was very prolific for me last year. Fruits were a deep smoky brown-purple color. Available from Seed Savers' Exchange.

Spudatula is my favorite... PL variant of Black from Tula.

One cannot describe "taste", grow one and try one.

I can describe the taste of black tomatoes, I think they're awesome. Black Krim was the first black I tried and it was fabulous, different from red tomatoes, but marvelous. Hubs loves Black Cherry, and he likes Brown Berry and Chocolate Cherry too, he thinks they're wonderful.