It may be illegal if you identify the individuals without their consent. You should also be careful about identifying the companies without their agreement as using their name may be construed as endorsement by them of your project.
Otherwise, provided what you say is factually correct, there could be no objection to statements such as "a top executive of a leading bank said this software was 'fabulous'". If you are using the statement in any sense of advertising you should keep the original attributable statement on record in case you are called on to substantiate your claim.