No, it's perfect for me, but I don't have particularly big hands. For a point of comparison, it's every so slightly tinier than my Xbox Series controller, and holds better than it. I always found that one tends to slowly slip forward out of my grip (=towards my belly) because of its tapered shape.
In contrast the Ultimate reminds me a little of the Gamecube controller, because it's slightly more concave below, where the ring fingers come to rest, and that helps stabilize it.
My single gripe with it is the dpad, which coming from the Xbox Series feels like a bit of a downgrade : not clicky, a tad mushy. I've known worse, but it's not the best. Fortunately that's not a dealbreaker for me as I don't use it often