I grew up on these. My (step)grandfather has been propagating the seeds of the plants his parents brought from Poland every year (he is in his 80s now). He's happy to share them with anyone and to talk about them, and gave someone some seeds one year. The next thing he knew, they were in a gardening catalog as heirloom tomatoes (something we'd never heard of till then... they were always just Grandpa's tomatoes). Now Grandpa's tomatoes are on amazon.com... life is funny.
Anyway, they are fantastic sandwich or burger tomatoes because of their size and density. Each one can weigh about a pound and is softball sized at least. They have a sweet flavor.
Less than 1/4 of the seeds germinated, and even though I nurtured and protected them with great care, they failed to grow more than a couple inches. I'm not a novice gardener, so would have expected better results, especially with the extra care I gave them. I really wanted to taste these tomatoes, and harvest a few seeds for next season. It was disappointing, but I may give them another try.