The tractor plows 4 crops, but it can also plow 1, 2, or 3 crops that have been harvested already. The tractor is a lot more faster then the person (i think). The gas recharges itself (for me, it doesn't take long because I don't have a large garden, only 2 mins to recharge)... It costs 60 coins to do 4 plows, you get 4 experience points (unless you plow 2 slots, you'll get 2 experience points, and I don't think it'll charge you 60 coins for plowing 2)... regular plow by person costs 15 coins. (15x4=60)... so it really doesn't make a difference if you plow the land yourself, or use a tractor, you're spending the same amount of coins anyways.
Some people might like it, some people might not. The tractor did cost way to much to buy though... but I manage to get my money back by harvesting. The tractor is good when you have a lot of plowing to do.
Hopefully I made sense, it's past my bed time lol.