Geeknamese
Explorer
I've tried and in my first campaign, it basically went unused for many of the reasons other have posted. It just wasn't very inspiring or fun, it felt like I was put into a position to have to reward players for playing their characters how I thought they should play them, and--mostly--I just never remembered to give it.
In my current Curse of Strahd game, I use a version of inspiration inspired by the Angry GM.
INSPIRATION = INSPIRED ACTION(inspired by the Angry GM)
Each session, each player will start with one inspiration token.
The token can be 'spent' to take an "inspired action."
When you take an Inspired Action, you can either gain advantage on an ability check, attack roll, or saving throw OR you can give advantage to someone else’s ability check, attack roll, or saving throw provided you are in a position to assist them directly in some way OR impose disadvantage on someone else’s ability check, attack roll, or saving throw provided you are in a position to hinder their action directly in some way. Whatever it is, the Inspired Action MUST somehow connect to one of your Personal Characteristics (traits, ideal, bond, or flaw).
After spending your inspiration token, you can get it back in the same session by Claiming a Setback. To Claim a Setback you must either impose disadvantage on one of your own ability checks, saving throws, or attack rolls based on one of your Personal Characteristics OR make a decision that creates a significant story setback, obstacle, or hindrance.
This is really similar to the way FFG’s Star Wars handles “hero/plot” points but it’s a resource trader between players and the DM so it’s less driven by personality traits and more by need. There is a double sided token on the table. In those times that the players really badly need something to happen or succeed, they can use that destiny token to gain a benefit. When they use it, the token is flipped and then becomes a resource that the DM can use when he needs it. Could be real nice when you have those encounters where, as a DM, you really wish the BBEG recurring NPC made its save to escape to fight another day but he failed the check horribly or something similar.