I had them and hated them. D'Addario halfs sound much more similar to rounds than flats. And, as BassBob1 said, they feel rougher and sharper than rounds. If you want a bit brighter string than "typical" flats, try D'Addario chromes.
Same experience here. In theory they seemed they would be perfect. Hated them and was very surprised. Expected a softer, smoother feel.