Yeah, using too much is going to make your food taste gross, just like adding too much salt would too. I also think it might not be suitable for every dish, so I think there's some experimentation required. For me, I like to add it to things that have a lot of tomato in them (like a sauce) or when I feel like there's something "missing". I find it rounds out the taste.

Maybe while you're cooking, taste your food before and then immediately after adding some msg, taste it again. It won't be like a huge, in your face difference - it's pretty subtle imo. Then again everyone's tastes and taste buds are different and it might just actually not be for you!