Do you know what rootstock it was on? Gisela should be more precocious than Mahaleb or Mazzard. Also, the pollination situation might matter. I agree that varieties that do well on West Coast might be worthless on the East Coast. However, Black Tartarian was very popular in England and was highly recommended in "The Cherries of New York" by Hedrick. Here is the description of BT by Hedrick:
Favorite dooryard and roadside sweet cherry. Tree is adaptable to different soils and climates; productive, healthy and robust; bears regularly, lives to old age and grows to prodigious size; comparatively free from brown-rot. Cherries not as large as some similar sorts, but have attractive rotund form and glossy black color and are a delight to the palate; handsome purplish-red flesh is firm and crisp, yet juicy, with a sweet, rich flavor which all agree is "very good to best." A little too soft to handle well in harvesting and marketing or to hold its shape as a canned product, but for home plantation it is one of the best. Introduced to England in 1794 from Circassia, by Hugh Ronalds, as Ronald's Large Black Heart, and in 1796 John Fraser introduced a variety, a native of Crimea, as Fraser's Black Tartarian. Both turned out to be the same. Black Russian, listed by some firms, is probably Black Tartarian as it is used many times as a synonym. Tree large, vigorous, upright, vasiform, productive. Fruit matures early; less than 1" in diameter, cordate, compressed; color purplish-black; flesh purplish-red, with dark colored juice, firm, meaty, crisp, pleasant flavored, mild, sweet; of very good quality; stone free.