MES - Manufacturing Execution System recommendations

Would love to hear about peoples experience with implementing MES. Anything to look out for? Benefits and real success stories?

The topic is not very well covered and most of the information found, is very biased, as it is written by the MES companies own marketing people.

Is there a real ROI value, or is it just a fancy buzz word?

Thanks

Manufacturing Execution System is effective whilst it is designed and configured to the use of the manufacturing industry by their users wisely, I mean gamification of manufacturing activities with appropriate integrations (needed and essential) and take actions based on the triggers (output) from the MES, it would be essentially great to have it integrated with ERP to realise the ROI in true sense