I am an Esperanto speaker, so I can say that this is not really accurate. Esperanto isn't a Romance language: it's got a lexicon that was drawn haphazardly from many different languages—not just Romance ones, but also Germanic and Slavic ones—in ways that render the source words difficult to pronounce and very often result in words that are confusingly non-similar to the original. For your past vocabulary to really contribute to knowing Esperanto, you'd probably have to know English, French, a dash of German, and maybe some Polish, and even then, the language is filled with false friends and idiosyncratic choices. (From English, for example, it drew the word boato for 'boat': pronounced "boh-AH-toh", making it sound nothing like the English word!)

And "the knowledge of Esperanto can be transferred to other prominent languages"? Only in the most cursory ways! Esperanto's vocabulary is also deeply minimal: for example, it makes antonyms from the prefix mal-, so that 'big' is granda and 'small' is malgranda, and it makes heavy use of affixes and word-combining to generate new chunks of vocabulary: a school is a learn-place (lernejo), lunch is day-eating (tagmanĝo), a dictionary is a word-group (vortaro), and so forth. This is great for making a minimal vocabulary that can be easily learned, but it means that you get only a tiny fragment of knowledge that's transferrable to other languages.

I could go on about how the structure is actually deeply unnatural and reflects several odd choices, or how the pronunciation involves tricky to near-impossible consonant clusters (e.g. because s is pronounced as 'ts', the word eksciis 'realize' has the cluster kssts!), but it's really not a well put-together language in the way that this seems to imply it is.