If you kind of liked Air Traffic Controller, this game is similar, but more entertaining. It's micro-managing, with lots of units and actions to perform. If you want to get the highest (gold) rating, you have to multi-task like in ATC, but the jobs you perform are way more varied, and the stress is more palpable. I mostly got through ATC, but didn't bother getting high scores because I didn't like the pacing and the actions were too repetitive to be fun.
Emergency DS ranks you on time, so a gold mission rating is earned for around 2 minute completion. Perfect for quick play sessions.