Esperanto was a good idea, but sadly suffers from some unnecessary problems, in addition to grammatical inflections.
The vocabulary was drawn almost at random from a number of European languages, which means that individuals might recognise some words from their own, but anyone with even a smattering of more than one language has to remember from which one the Esperanto word is taken. (It would have been more consistent to try to develop a simplified Latin, as others have in fact done.)
Zamenhof also seems to have been paranoid about homophones; "post" in Esp means "after", so post as in mail and letters has to be "poŝto "...
Equally unfortunately, a Polish speaker is not really the best person to judge ease of pronunciation! For example, the everyday verb "to know" is "scii", with the c pronounced "ts" - a pronunciation nightmare for many nationalities...