Moderately. The US Foreign Service Institute rates Hindi Category III — about 1,100 hours to professional proficiency, harder than Spanish or French but easier than Arabic, Chinese or Japanese. Speaking comes faster than most people expect; the script and the gender system are the real work.
What is genuinely easy
The script is phonetic. Every letter makes one sound and
always the same sound. English cannot claim that — though, through, tough.
No articles. No a, an or the to worry about.
Shared roots. Hindi and English are both Indo-European.
Naam/name, maata/mother, do/two, teen/three
are not coincidences.
You already know hundreds of words. Everyday Hindi is full
of English: station, ticket, phone, doctor, hospital, computer.
What is genuinely hard
Gender. Every noun is masculine or feminine, and verbs and
adjectives must agree. Worse, the verb agrees with the speaker's gender
in the present tense. This is the single biggest source of errors.
Word order. Verb last. "I bread eat" instead of "I eat
bread." It takes a few months to stop translating in your head.
Retroflex sounds. त versus ट, द versus ड. English has
nothing like the distinction, and you will not hear the difference at first —
which is exactly why an app cannot teach it.
Postpositions. Hindi puts them after the noun, and they
change the noun's form.
A realistic timeline
Goal
Time
Greetings and basic politeness
2–4 weeks
Reading Devanagari aloud
4–8 weeks
Simple conversation
4–6 months
Comfortable conversation
1–2 years
Anyone promising fluency in three months is selling something.
Practise this with a teacher
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.