I seem to be able to climb hills in nearly any gear, though some are more fun than others. I had a fixie until last year when it was stolen. I set it up to a 66-inch gear, approximately. (chainring teeth / cog teeth * 27"). 66" is ideal for most purposes.

I even towed a lot of weight on my three speed, up my steep hill (fairly steep, anyway) before I replaced my cog. It's hard and slow, but I can manage.

Modern derailleur systems offer very low gears. They're nice, and I use them when I have them, but I can do without them. I'm not sure I could do as well in Vermont as I do here. Hills are much harder there, usually because of height, not steepness. Back in the 70's, the standard setup was 52/42 (or 52/40) in the front and 14-28 in the rear. Bottom gear was about 40 or 45 inches.

And if you keep using your super low gears, you'll never get better at climbing. My fixie is what taught me how to climb.

And then there's descending. Descending on a fixie with a low gear is hard and scary. But I like having the skill anyway.