Was David mainly upset about Uzzah's death? In I Chronicles 13, why was David upset?  Was it mainly upset about Uzzah's death because of the amount of responsibility that came with being God's anointed and being responsible for the Ark of the Covenant?
Lets take a look at the Passage of Scripture and see if we might determine just what happened.


  1st Chronicles 13:5 through 12 KJV So David gathered all Israel together, from Shihor of Egypt even unto the entering of Hemath, to bring the ark of God from Kirjathjearim. And David went up, and all Israel, to Baalah, that is, to Kirjathjearim, which belonged to Judah, to bring up thence the ark of God the LORD, that dwelleth between the cherubims, whose name is called on it. And they carried the ark of God in a new cart out of the house of Abinadab: and Uzza and Ahio drave the cart. And David and all Israel played before God with all their might, and with singing, and with harps, and with psalteries, and with timbrels, and with cymbals, and with trumpets. And when they came unto the threshingfloor of Chidon, Uzza put forth his hand to hold the ark; for the oxen stumbled. 
  And the anger of the LORD was kindled against Uzza, and he smote him, because he put his hand to the ark: and there he died before God. And David was displeased, because the LORD had made a breach upon Uzza: wherefore that place is called Perezuzza to this day. And David was afraid of God that day, saying, How shall I bring the ark of God home to me?


If I am reading this correctly David was not upset as much as he was afraid of God.

So the central question appears to be why was God so angry, and why was David afraid of God. So lets see if we can determine both of these reasons.


  1st Chronicles 13:3  And let us bring again the ark of our God to us: for we enquired not at it in the days of Saul.


According to this they had not even been trying to find the Ark of the covenant since the death of Saul which was some years after it was taken by the Philistines.


  1st Samuel 4:6 and 11 KJV And when the Philistines heard the noise of the shout, they said, What meaneth the noise of this great shout in the camp of the Hebrews? And they understood that the ark of the LORD was come into the camp.
  
  11 And the ark of God was taken; and the two sons of Eli, Hophni and Phinehas, were slain.


Although it is not readily apparent from Scriptures it was quite a few years since it had been taken. The Ark of the Covenant was taken several years before Saul's death and it had been several years since Saul's death, as David was king of Judah for 7 years and 6 months before becoming King of all of Israel.


  2nd Samuel 2:11 KJV And the time that David was king in Hebron over the house of Judah was seven years and six months.


We are not told how many years David reigned over Israel until the Ark was sent back by the Philistines, but it was most probably several years.

Apparently over the years they had forgotten that God had given very strict instructions about how the Ark was to be transported and by whom. A situation which David later rectified.


  1st Chronicles 15:1 and 2  And David made him houses in the city of David, and prepared a place for the ark of God, and pitched for it a tent. Then David said, None ought to carry the ark of God but the Levites: for them hath the LORD chosen to carry the ark of God, and to minister unto him for ever.


And he also charged the Levites and Priests with properly transporting the Ark.


  1st Chronicles 15:12 and 13 And said unto them, Ye are the chief of the fathers of the Levites: sanctify yourselves, both ye and your brethren, that ye may bring up the ark of the LORD God of Israel unto the place that I have prepared for it. For because ye did it not at the first, the LORD our God made a breach upon us, for that we sought him not after the due order.


And when this was done properly the Ark was then transported to Jerusalem and placed in the tent David had built for it. 

Hope this answers your question, but if you still have questions I will be glad to give you any other Scriptures which may clear it up for you.