If you're serious about improving as a GM, or about making your sessions better for a particular game, you need feedback. Feedback is tricky though. After all, you have your vision of what the game is, and your players each have their own. It wouldn't surprise me to find that in my L5R game with 6 players and me each person had their own unique view of what the game was, and what it was really about - aside from the obvious stuff we talked about in the beginning. Today I want to talk about ways to get the feedback you need, and it's not just about what and how, but when too.
Avoid Yes/No Questions
If you ask a group of people if they had fun in your game, odds are you will get a chorus of "Yes" without much thought. Even if people didn't enjoy the game itself you'll likely get this. They're not being deceptive either. You ask an easy question - as in one with limited and binary answers - and you will get the one that is least likely to cause further problems, or further questions.
Someone may even have had fun, just not in game. Maybe they enjoyed seeing some of the other players. Maybe they had a blast cracking jokes at the NPCs expense while off screen. Maybe they really really like building dice towers and hit a new record. The point is you don't know.
Heck, even if they are telling the truth, what did you learn? The overall experience of your game was positive. That's good, but that doesn't tell you what was positive and what was negative.
Instead I'd recommend asking questions like "What was the stand out moment for you this game?" or "What did you think of NPC X?" questions that don't have binary answers and require the player to think a bit. If everyone gives different answers for what they thought was the stand out moment, than you've hit a number of highs. If everyone has the same answer, then you had an amazing moment - and that's awesome - but you also want to make sure it's not the same PC getting the awesome moments everytime.
You can even ask questions about the bad parts of the game. "What didn't you like this session?" "Was there a scenario you would have run differently?" Get your players thinking, and listen to their answers.
Don't Take It Personally
It is easy to take critique and feedback about your game as a personal thing. Someone saying that they'd rather Situation Y played out like Z can sound a lot like they're saying your game is stupid, especially in the heat of the moment. Don't take it that way, and don't react negatively to it or try to defend the game. If you react or try to defend everything someone says went a way they didn't like they'll stop telling you what they think and start saying what they think will spare them the lecture.
Have some thick skin. You need it already for rule discussions, use it here as well.
Break The Feedback Down
Neil Gaiman has a quote for writing that is appropriate here. The quote goes "When someone tells you something is broken they are almost always right. When someone tells you how to fix it they are almost always wrong." The point here is that you need to listen for where things are wrong, but don't just take how the player would fix it as word from on high.
A player complaining about being in status lock for an entire combat, and saying you just shouldn't use status locks has a point, but their complaint isn't that their character was stunned all fight. Their complaint was that they could do nothing during a key moment in the game.
Listen to your players, but try to break down the core thing they're complaining about. Consider their solution, but don't be afraid to find your own.
A Bit of Time Gives Perspective
It can be good to take notes of the feedback you get, then read it again a couple days after game. With distance you'll have more objectivity. This is a good thing.
At the same time, it can also be a good thing to talk to some of your players between sessions and ask them about the game and things in it. Often times what irks a player during the session may settle into something the player really likes once they have time to think about it. With me I find this happens most often when it comes to the PCs being beaten in fights. In the moment I'm fired up, in character, and annoyed that I lost. Give me some time and distance, and suddenly I'm excited for the story possibilities and how the characters will grow from the experience.
Don't Be Afraid To Experiment
Let your players know you are doing so, but don't be afraid to give things a try. If someone wants combat to be more dynamic, then give it a shot. Throw people around. Be crazy with descriptions. If folks don't like it you can stop. If they do? Keep going.
Games are a work in progress. That is true for every game. Every session is an opportunity to learn, a chance to improve, and a great time to try a new thing to see if it works and if it's worth the effort.
Give it a shot. Have fun with it.