Learners expect the script to be the wall and it is not: Devanagari is phonetic, finite and usually readable within six weeks. The real difficulties are two, and they are both grammar.
Every Hindi noun carries a gender, adjectives agree with it, and — unlike Spanish or French — so does the verb. Your own gender appears in your verbs in every sentence you speak. There is no dependable rule for guessing, so gender has to be learned with each noun from the very first day. Learners who decide to "do gender later" end up relearning several hundred words, which takes roughly ten times as long as learning them correctly once.
In the completed form of a transitive verb, the subject takes ने and the verb agrees with the object instead. मैंने किताब पढ़ी — the verb is feminine because किताब is, regardless of who is speaking. This is called split ergativity, the rule is one sentence long, and the exceptions are the entire subject. It is the single thing self-taught learners most reliably get wrong and then fossilise.
No articles. No ser/estar distinction. Almost no irregular verbs. Spelling that matches pronunciation. Hindi gives back more than it is given credit for.
Reading an answer is one thing; being corrected while you say it is another. EkGuru tutors teach one to one from $6 a lesson, and most offer a trial.