I love designing so this app is right up my street. It gets quite addictive and could become expensive if you get impatient and want to complete the rooms faster. I like the daily rewards and I get a buzz from receiving my room scores!
If the app gets stuck in the blue screen that says Live Challenges, you could try this: close the app, go to Settings > Apps & Games > Manage All Applications > Design Home. Then tap on Clear Cache. After the size of the cache has reduced, tap on Force Stop, then Clear Data.
That's what I did to get the app working again. Other little bugs, such as when the app freezes, seem to be fixed by closing the app and tapping Clear Cache, then opening the app again (might need to repeat that a few times).
The odd bug aside, I love playing this app. Fun, plenty of challenges, great items. I find it a great distraction from worry (and work).