This game resembles a bit The Elder Scrolls IV: Oblivion in style, with many RPG and other similar elements to it, but without all the freedom of exploration.
RPG gameplay works mostly for me, and it's something which keeps a game
interesting to the end. Getting stronger and learning new abilities is
always interesting and exciting.
This is one of the very few RPG games I have played where spells are
actually useful (for something other than just healing purposes). For
example Oblivion is very difficult to play if relying mostly on spells
to do your fighting, but in Fable the spells are truely powerful and can
really be used as your main weapon. In theory the entire game could almost
completely be passed by using spells alone (except the few places where
using a weapon is mandatory). Learning a spell felt immediately useful
and not a waste of time, like so many spells in so many other RPGs.
There were much fewer quests and sidequests than in Oblivion, which made
the game a bit short (but still much longer than most modern linear FPS
games). There was some exploration element to the game, but not much
(the world was not free to be explored).
The game gives the impression that the alignment modifier is somehow
very important (doing good things improves your alignment and doing
bad things makes it worse). However, it results that your alignment
is not, after all, all that important and it doesn't really matter.
Basically the game makes you worry for nothing.
Related to this, the game has one of the most incomprehensible features ever: There are good side quests and evil side quests, and if you ever accept a quest at the guild, you cannot cancel it. Ever.
This is a problem because if, for example, an evil side quest requires you to kill all the villagers, and passing through that village in question is mandatory to advance in the main plot, you simply cannot skip that evil side quest. There just is no way. For whatever reason, you simply cannot go through the village without doing the evil quest because the game doesn't allow you (if you try to exit the village, the game will simply load an autosave it made before you entered it; you cannot get past the village, period).
The game doesn't make it clear which side quests are good and which are evil.
If it's against your principles to kill innocent villagers and you mistakenly took the side quest, you are stuck. Unless you happen to have a save from before you took the quest, you can't advance in the game without doing that quest.