I'm posting this here because I just started learning Korean (today is my 10th day), and although I'm interested in everyone's opinions, I'm especially interested in those from Korean learners and native speakers.
I was surprised and disappointed to find out Hangul wasn't nearly efficient as I was lead to believe. I guess to a people who were used to Chinese characters, which can be made from 214 different radicals and aren't usually phonetic, Hangul was a godsend. Only 24 Hangul letters are used to make Hangul blocks, and all letters are (more or less) phonetic. So it's much simpler than Chinese. But how unfortunate that they stopped there. Whole words aren't very phonetic, and clusters are cumbersome.
In comparison, Japanese Kana is much simpler, imo. Almost 100% phonetic, and no "blocks". Yes, there are more letters (over 100 if you include hiragana, katakana and modified forms), but that's a small price to pay for being phonetic.
So despite all the hype I've heard about Hangul being the world's most efficient writing system, I find kana to be more so. How about you?
I wanted to learn Japanese some years ago, and I was extremely happy when I learned the hiragana and the katakana. But I was told by the teacher that in order to write to someone in Japanese or to read Japanese websites (news, blogs, etc.) I needed to learn the kanji also. And that's what stopped me to keep pursuing my Japanese studies: I realized that I'm extremely bad at learning each particular kanji with their two readings (on-yomi and kun-yomi), so I was devastated when I decided to left Japanese. In my frustration I though ma ny times that I didn't understand why they needed the kanji, having hiragana and katakana (two beautiful writing systems).
I started recently with Korean. My first impression about hangul (even before knowing that it was called like that) was that it was messy and very similar to kanjis but more "squared" and "circular" (more "plain"). Then I started step by step. I loved the idea of combining some basic characters and form blocks. For me that was mindblowing: it was like hiragana but with less characters. It is true that is not very phonetic, and in that sense I think it loses against Japanses Kana, but after learning some basic rules (ending consonant goes up if the next character starts with vowel, the double vowel sounds, etc.) all starts making sense.
In summary, my personal opinion (also not an expert) Japanese kana is more efficient from the phonetic point of view, but Korean hangul is more efficient speaking about the characters/words formation (blocks are awesome!).