Driving with Overdrive off or on?

Ok... I have what is actually a 2002 Accent, not a 2001 was I posted before.

Anyhow, my wife drives the car with the Overdrive switched "on" all the time as she says it makes less noise.

I like to drive with Overdrive switched "Off" unless I'm on the freeway as it seems the car accelerates faster and slips in and out of gears better.

It is an automatic and I understand regardless to OD being on or off, it only uses the Overdrive gear when at high speeds.

So... does it make any difference around town?

Should I leave it off when I'm driving around town, or leave it on all the time.

Any information on what it's all about is appreciated!

Generally, the main difference is gas mileage. In the transmission, Overdrive (O/D) is the highest gear. Overdrive allows the engine to have less rpm with higher speed in order to have better fuel efficiency. When you switch it on, you allow the transmission to shift into overdrive mode after the certain speed is reached, depending on the load, it can usually be 30 - 40 mph. When it's off, you limit transmission shifting by its third speed. In my opinion, overdrive should always be on in normal driving conditions.
There are times where you may need to switch it off, such as in mountains areas. For example... the automatic transmission automatically shifts from OD to the 3rd gear when it feel more load and when it feels less load it shifts back to the O/D.
Under certain conditions, such as driving uphill or towing a trailer, the transmission can not decide to stay in OD or to shift into 3rd speed and it starts to shift back and forth. That's the time you may switch it off and help the transmission to decide. You also may need to switch it off when you want to slowdown using the engine braking, for example, driving downhill.
Hope I was helpful.