Hi Phani,
For BI / BOBJ, you should have good understanding database fundamentals and good technical aptitude.
What if they failed to meet their commitment once you passed the certification. Moreover, you should not select a course, based on what others promised. You should go and select the course on your interest. For every module, there is always a market. Know your interest and then join the course. If you really like ABAP, then go for it. Please do not choose the course, as somebody suggested you to do it.
It is not difficult, provided if your fundamentals are crystal clear.
Best Regards,
Ravi