I test rode my first folding bike (Brompton) last fall and I loved it. Yes it is different than riding a non folder but you get use to it pretty quick. The two things that I noticed for myself is, one it felt weird when I came to a stop and put my feet down and couldn't feel the top tube between my legs. Normally I rest a bike between my legs and this frees up my arms to go into a bag or something. Second, maybe some people do it but I didn't and that was stand while I was riding up a hill. I am so use to riding my single speed riding in a standing position is second nature, on the Brompton, it just didn't feel right.
All in all I really liked it and I am very picky. It was only the fourth bike I liked right away on a test drive and I can tell you I have tried hundreds of bikes. I use to work at a bike store, so I had access to many bikes, plus I would ask customers if I could try their bikes. The Brompton is nice and I am still contemplating buying one this year but they are expensive.
Good luck on your test ride, it just may be the bike for you.