Baldfalk's partially right -- two threads already have threads that probably would answer your questions if you took the time to read through them.
Need Help Improving on 7k/8k ->
DJ Max Trilogy Helpfulness Thread.
New Music Games (this thread) ->
Popstage,
EZ2ON, and
Krazy Rain are among the most discussed alternatives, although EZ2ON died last month.
I don't see anything wrong with asking about merchandise or revival lists, although, having actually given some thought about it, learning Korean is something completely separate from talking about the gameplay of DJ Max or alternatives, and thus I've moved it to General Discussion.
As an aside--
I'm normally
very lenient about keeping threads, because good threads will always find themselves back to the top and outdated or garbage threads inevitably sink to the bottom. For a great example, take a look at all the threads asking for Trilogy help even though we've got a Trilogy Helpfulness Thread; there are three or four where there used to be six or more.
I've yet to see any complaints about my style of moderation, even though ideally, I'd like for posters to try to look through the information that's already posted before moving on - it's not that hard to skim, certainly at least through thread titles.