personally I thought the 1st one was awsome, dont know if that makes my view bias.
In fable 1, you could be good or evil neutral. you could go from being solid evil to good and nothing would really happen. you apperance would change, people would be scared of you, and shops may give you a discount.
How ever in fable 2... the effects of being good or evil actually play some role in the game. You be faced with a few decision that will change the game. Like if you help the farmer, his farm will thrive in the future and get alot bigger, but if you take the other quest and kill him or what ever it was, it probably turns into a bandit camp or somthing (IDK I went the good route).
Yeah I also found it strange fable 2 has atleast 10 times the land that fable 1 has but the main story doesnt feel as long.
If you dont want to drop the 50$ for it, I'd atleast rent it or borrow it off a buddy.