It's a phrase used to express:
* Curiosity about something unique or noteworthy.
* Inquiry about the reason for something being considered special.
* Skepticism or disbelief about something being claimed to be special.
The context will determine the specific meaning. For example:
* "Endundu vishesham?" (said with a curious tone) could mean "What makes this special?"
* "Endundu vishesham?" (said with a skeptical tone) could mean "What's so special about that?"
The phrase can be used in both informal and formal settings.