The short answer

Korean's difficulty is not the alphabet, which is genuinely learnable in an afternoon. It is that spelling and pronunciation come apart through layered sound changes, and that the consonant system makes three distinctions where English makes one. Both are audio problems, and both are invisible to an app working from a transcript. Here the tutor hears your voice directly, and Hangul is shown with a Latin reading beneath it so a beginner is never locked out.

Korean is famous for having the most learnable writing system in the world, and that reputation is deserved. Hangul is systematic, phonetic in design, and most people can read it slowly within a day.

Then you listen to somebody speak and almost none of it matches what you learned to read.

Spelling stopped tracking speech a long time ago

Korean orthography is morphophonemic: it preserves the underlying shape of a word rather than its surface pronunciation. That is elegant and it means the same root looks the same everywhere. It also means a stack of sound-change rules sits between the page and the mouth, and they all apply at once.

옷만 is written with a ㅅ and an ㅁ and comes out as onman, because the ㅅ neutralises to a t and then assimilates to an n before the nasal. 좋겠다 goes through aspiration and then tensification. Learners are usually taught these rules one at a time, late, as curiosities. In speech they stack, constantly, from the first sentence.

The three-way consonant problem

Plain, aspirated and tense. English has two categories at best and hears all three Korean ones as approximately the same sound.

This is a pure audio problem. You cannot read your way out of it, and you cannot learn it from a description, because the description is only useful once your ear can already tell them apart.

Your audio here goes to the model directly rather than being transcribed into text first. That matters enormously for exactly this: if you say the plain 달 when you meant the tense 딸, a transcriber will very often give the tutor the word it thinks you meant, correctly spelled, and the tutor will have no idea anything went wrong.

Politeness is a choice you make in every sentence

Korean speech levels are not decoration and they are not optional. 해요 and 합니다 and 반말 encode a relationship, and choosing one is the first thing you do in any sentence.

Sessions default to 해요, which is the register that will serve you with almost anyone while you are finding your feet, and the tutor holds the same standard in what it says back so the model in your ear matches what you are aiming at.

Hangul, and the reading underneath

The tutor writes in Hangul, because reading it is part of learning the language and the investment is genuinely small. A Latin reading of your own speech is shown underneath by default, and can be switched off in a moment by anybody who does not need it.

What a session is

Unscripted conversation with something you can interrupt, backed by an authored CEFR syllabus of 293 items from A1.1 to C1, of which 102 are capabilities: concrete things you can do rather than grammar points.

Going to Korea

Travel Mode changes the app for the length of a trip: rehearsal before you go, one real-world mission a day while you are there set in the city you are in, and a debrief with your tutor afterwards. Korea is a strong case for it, because service interactions are fast and formulaic, which means rehearsing the exact exchange that morning genuinely carries you through it.

The five Korean tutors

Every language has five, each from a different place and each sounding like it. You can switch whenever you like, and the app remembers where you are regardless of who you talk to.

JisooSeoul
The clear, neutral Korean of the capital, and the standard nearly all course material is built on.
MinjunBusan
Southern Korean with the strong pitch movement and warmth of Gyeongsang satoori.
SeoyeonJeonju
The gentle, melodic Korean of the Jeolla region.
JunhoDaegu
A Gyeongsang accent with the punchy intonation and distinctive rising-falling pitch of the southeast.
DohyunJeju Island
A relaxed, island-paced rhythm from the south, vowels softened toward standard Korean.

What English speakers usually find hard

These are drawn from the pronunciation patterns the tutor listens for in Korean. Because it hears your voice rather than a transcript of it, they are things it can actually notice and work on with you.

Three stops where English has one: Plain, aspirated and tense. 달 (moon), 탈 (mask) and 딸 (daughter) differ only in this, and English speakers hear all three as some version of a d or t. Plain is soft, aspirated has a strong puff, tense is sharp with a tightened throat and no air at all. This is the single hardest thing in Korean pronunciation.
ㅓ and ㅗ are different vowels, and ㅡ is a third: ㅓ is open and unrounded, ㅗ is rounded. 서 and 소, 너 and 노. English speakers collapse them. Then there is ㅡ, which has no English equivalent at all: tongue high and back, lips spread, and it appears constantly in endings like 으세요.
What you write at the end is not what you say: Many final consonants neutralise to one of seven sounds and are not released. 옷 ends in a t sound despite being written with ㅅ. Then, if the next syllable begins with a vowel, the consonant slides across to start it: 한국어 is han-gug-eo, not han-guk-eo.
Sounds change when they meet, and the spelling never updates: Stops become nasals before nasals, so 입니다 is said imnida. Plain stops tense after a stop, so 학교 is hakkyo. ㅎ merges with a neighbouring stop and aspirates it, so 축하 is chuka. None of this is written down and all of it is constant.
Even syllables, no English stress: Korean gives syllables fairly equal weight and has no lexical stress that changes meaning. English speakers importing strong stress and reducing everything else to a schwa sound distinctly foreign. Also worth knowing: in the 해요 level, a statement and a question can be identical words, with only rising intonation marking the difference.