English isn't that hard to learn, it's just hard to speak. Its grammar is simple as hell and can be stretched really far.
I can type a sentence like this.
This I can type a sentence like.
It is not a crime to wildly split infinitives.
Let's go over regular conjugation in Spanish using "hablar":
Tense | First Singular | First Plural | Second Singular | Second Plural | Third Singular | Third Plural |
Present Indicative | Hablo | Hablamos | Hablas | Hablaís | Habla | Hablan |
Preterite | Hablé | Hablasteis | Hablaste | Hablamos | Habló | Hablaron |
Since this is extremely time-consuming, I'm just going to say that there are 7 more that I didn't list; the past participle is "Hablado" and the present participle is "Hablando".
Now, let's do one for English, using the standard verb "to talk":
First Singular | First Plural | Second Singular | Second Plural | Third Singular | Third Plural | Preterite | Past Participle | Present Participle |
talk | talk | talk | talk | talks | talk | talked | talked | talking |
Yeah, I didn't really need a table for that. The main issue with English is that there are so few regular verbs and no sense of phonics. Words like "think" with just an irregular past tense will still be understood if done wrong ("thinked"). Words with completely irregular conjugation like "to be" or "to do" or "to have" are often irregular in other European languages anyway. Esperanto won't exactly help any more than English will, since Esperanto is just as horrible euro-centric as English.
Esperanto's main advantages are no irregular verbs and standard pronunciation, which basically makes it English if English were Spanish.
EDIT: Haha, I just used the subjunctive form of "to be" there. I can't think of any other words that have subjunctive forms in English, though.