Yep, agreed - not worthwhile spending 3 hours on a lounge at Dubai. You'll find that by the time you get into the terminal... it takes time for security clearance... and, depending on what time you arrive at Dubai:

- plane circles above dubai for 20 mins due to traffic
- if your plane gets a stand at the actual terminal, consider yourself lucky. If they have to park it remotely, be prepared for a 20-25 min ride in the bus to the terminal
- once you get into the terminal, be prepared to queue for some time for security.

You can easily spend the time at duty free in t1 and then walk over to t3 where you'll find that time has flew by!