MSBI limitations

Hi Guys,
    Could you please tell me what are the limitations of MS BI ?..I am getting the question recently from my senior officers?  Currently in our project, we are using Informatica as a ETL tool and Cognos and BO for Cube and Reporting purpose..They are  planning to go into MS BI completly as it has IS , AS and RS...but before moving into MS BI, hey want to know what are the pros and cons/advantages/drwabacks of MS BI than its competetive tools?..

I would really really really appreciate your inputs...