However, a lot of conlangers have noticed that there are a lot of consonant clusters and basic phonemes that don't seem to have nice analogues in many languages - like Esperanto's affricates, affricate & fricative clusters, etc.
On top of that, the language is phonemically regular in the sense that there are no natural-sounding phonemic irregularities that one might normally expect.
In my view, Esperanto sounds fine. It has it's own aesthetic. Though at the same time, I find that because a lot of Esperanto was designed without a global audience in mind, there are a lot of "approximations" to what Zamenhoff, the original creator of Esperanto, maybe had anticipated that the language would sound like.