This is highly personal and we are sure many people will disagree. Still, it is needed to explain how we view this class in general in order to continue. Once more, please, if you want to argue feel free to create a new thread. We are not going to answer anyway. We believe that Magus is a difficult class to play with lots of potential. He is also one of the classes (Mabinogi Gold) where spec does matter a lot. One could say this is not a class that everybody can play at a level even close to its potential.
To give an example, if the same guy puts same effort into playing (let us say) a Sorcerer and a Magus, he will play the Sorcerer to (again let us say) ~70% of his potential but Magus to 50% of his. However, if someone manages to play a Magus to his full potential, in our opinion, he offers more than most other classes at same levels (cheap Mabinogi gold).
Also, it should be noted that Magi are late bloomers. We require many of our abilities to actually do what we are supposed to do. Best example is the Demonology tree that simply is bad at RvR until Rank 30 (or even 31) and becomes extremely good in an organized party after that point in Mabinogi.