Haba seems to be widely respected brand for blocks, and these do not disappoint. It's worth noting that it's very much a German product, coming with small catalogs written entirely in German. But it's not as if anybody really needs an instruction manual for blocks. More importantly, the measurements are metric and so they don't fit neatly with American products like Melissa & Doug: Haba's blocks are based on multiples of 4 cm (1.575 inches), whereas American blocks mostly use a "standard unit" based on multiples of 1.375 inches.
They are relatively pricy - $1.65/block currently compared with $0.90 for Melissa&Doug. Some of the reason for that would be the wood: Haba uses beech, a denser wood than the rubberwood others use. I'm not sure it's worth it in itself, but I was impressed by Haba's robust line of expansion kits, and I wanted blocks that would be compatible.
This basic set includes six cubes (4cm each side), four triangular prisms (a cube cut diagonally), six short rectangles (8x4x4), four long rectangles (12x4x4), two "bridges" (the 12x4x4 piece with a half-circle 4cm in diameter cut out of one side), and four cylinders (4cm diameter, 8cm long).