Pros
In my personal experience, Mphasis is a heaven company to work with if you are in a long term project. Comfortable work timings, Work from home facility, work life balance. But its upto you on how you groom yourself technically, because they wont force you to do so by giving some pressure as in other companies.
Cons
Internal project mappings are not good. You will come across a openings for your skill at one side and on the other side they will be asking the employee to leave the organisation for the same skill. As because of running short of projects. Personally this happened to my friends. Top level management wont give you a feel like you have been working under a wise people with a vision, might be there are few exceptions, but mind that its only few. Relationship with HP is not clear. Some say HP is going to sell Mphasis, some will say It will be merged with HP soon. So it wont give you a feel like you are in a safe place, even 8 yrs experienced in the company are feeling the same.