I have a 2004 Verona with the same Hold button on the console. When you have it in the hold position, you'll see the word hold on the dash. This allows you to disengage the transmission altogether. You'll need to start out in first, then shift to second, onto third and finally fourth gear. It's a stick shift without the clutch. If you are wanting to pass and are already in fourth you'll need to downshift to third to get that extra boost of power. The automation of the automatic is converted to manual, you'll have to do the shifting yourself.
This is a great way to feel like a kid again without all the excercise from your left foot on the clutch. The hold button also allows you to stay in first gear while traveling on snow for a little extra traction, kind of like granny gear in an old 57 Chevy truck I had as a teenager.
Until Suzuki finally got the ECM replaced I had bypassed the computer problems by using the hold button. I understand the Forenza has the same thing.
Just don't forget that when you are at a stop light and you're sitting in fourth gear, you'll lug that engine just like you're learning to drive a stick shift. The car just won't go anywhere in fourth at a stand still. Talk about embarrassing.
After awhile you'll like having this great little feature. Quirky little car, isn't it???