Some of Balakumaran's works are gems. 'Irumbu Kuthiraigal' (I don't accept the author's views but the story is intriguing, esp the poems), 'Thayumanavan', 'Appam vadai thayirsadham' are all very well worth a read. I don't remember the names, but, some were really drabs. 'Udaiyar' starts magnificiently, but, is a let-down.
IMHO, Balakumaran is a 'mixed' writer. He writes some good ones and some really bad ones. I haven't read much of Thi.Ja to compare.
Swetha, very interesting comments. I want to read Mohamul once more before responding to you!! I don't remember much other than the basic storyline, since I read it a very long time ago.
BK is undoubtedly a talented guy, but repeats a lot, atleast used to. Just like you I liked Irumbu kudhiraigal too although did not agree with much of what he said.