Is 2.5 cubic feet enough for one person?

Yes for most singles and couples. It holds roughly a week of frozen food for one person, or a few dozen meals, but not a large stock-up of a whole family's groceries.

Does it need to be defrosted?

Yes. This is a manual-defrost freezer, so ice builds up on the walls over time and you need to empty it and let it thaw every few months to keep it efficient.

Can it go in a garage or unheated space?

Check the label for the climate class before you buy. Many small chest freezers are rated for indoor room temperatures only and may not hold temperature in freezing garages.

How is it different from a small upright freezer?

A chest holds cold better and usually fits in tighter spaces, but you stack food and dig for it. An upright has shelves and easier access but loses more cold when the door opens.

Does it come with baskets?

Most units in this size class ship with the freezer alone, sometimes with one hanging basket. Check the box contents for the specific model before you buy.