We go every year over the 4th (except this year because of fiance's golf tournament...). For an 11 day stay, it's fine. On the 4th, we avoid the parks and go to Downtown Disney, eat dinner at Narcoossee's and view the MK fireworks from the restaurant's veranda, then fight our way into the MK. If you're going for a shorter period of time and can't lose a day, you may be disappointed. The MK often reaches capacity in the morning and only resort guests are permitted inside the park. If you're planning on staying on site, you will still be able to enter, but, in my fiance's famous words, would you want to?
July 4th is traditionally a frustrating day for guests who want to experience as many attractions as possible. But, the entertainment and fireworks are first rate, plus the MK stays open until midnight (I remember when it was 2:00am). If you're able to add an extra day for touring, you won't regret going during this time. It really depends on the length of your stay. Go to the MK later in the evening on the 4th. It really clears out after the fireworks. By the way, the best place to watch the fireworks is from outside of the MK on the 4th. Good luck and enjoy your trip!