is hard to give u an exact detail list of issues with your set. coz there r lot of setups when comes to modded wiis. but here r is a list that is specific among korean sets:
1. u cannot firmware update through nintendo online via wi-fi.. u must always firmware update through backend, which is a complicating process (just google it). usually people just send to shop to do it, but must pay money.
2. Is hard to "unmod" it. your wii will be forever modded.
3. u get the dreaded 003 error (unrecoverable) if u do point 1 and 2 (sometimes is not u, but your dog that did it)
4. warranty lor, which is usually none, or warranty from shop. never from nintendo.

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Added on June 14, 2010, 8:38 am
its very high chance is soft mod, and korean. hard mod nowadays is not very popular. there is no "about" page. coz is not very easy to put an engineering subject in 1 page (i heard it takes 4 years to be an engineer). but u can go to hacking website/forums and u can read all about it, in more then 1 page of course. but let me simplify, if u run your games other than through the disc channel, then your wii is soft modded.

i proud have wii
but relly dont have time to play
zelda twi prcss stil not finish yet