John, it’s just like anything else; there are good horn loudspeakers, and not so good. They got their bad reputation from the PA designs of the "dark ages" (1940’s-50’s). The old Altec A7 was a very popular PA loudspeaker (my teenage band had a pair), and was incredibly colored. It was fine for sound reinforcement, but recorded music, especially voices, sounded ridiculous coming out of it. Cup your hands in front of you mouth and speak or sing; that’s what they sounded like. J. Gordon Holt used the obvious term "cupped-hand vowel coloration" when reviewing such-sounding speakers.
Horn design has come a long way since then. I knew a Wilson/Vandersteen dealer (Brooks Berdan, R.I.P.) whose personal home loudspeaker was a pair of Jadis Eurythmie’s, which sound incredible! You pay dearly for them, however.