THE CURRENT preoccupation of city hall observers is judging Mayor Marion Barry's first year in office. The value of judging the first year of a four-year term is questionable.But in a city where local politics is still in its infancy (this mayor being only the second in District history), there is constant interest in what the District government is growing into. That interest is also fueled by the way the city was run for so many years when a powerful, mostly white Congress ruled over the mostly black city. Now that city residents elect their own government, the question is: What will the city government do? Will it be any better for the people in the city?

There is, also, understandably, fascination with the new mayor. His predecessor was generally thought to be a nice man who was not up to the task of cracking the whip on a sluggish, unresponsive bureaucracy or able to envision a better future for the city. The new mayor, once a dashiki-clad street activist, who has journeyed through the school board and city council to the city's top job, is carrying the flame for all the '60s radicals and up-and-coming blacks who wanted to purge the old politicans and change the world.

Now it is one year later. Has the home-rule government under Marion Barry made a difference? In a word: yes. The mayoral campaign of '78 brought the top issues in the city -- housing, education and economic development -- to the public eye. City politics has blossomed, with every interest group claiming some responsibility for the mayor's victory and demanding that he pay attention to its needs. There is faith that this mayor wants to do some good. And the mayor has brought new energy to the District Building. That energy has been manifest in his appointments to top city jobs. Elijah Rogers, city administrator, and Robert Moore, housing director, are two appointees who have distinguished themselves and added to the District government in their first year on the job. The mayor has also been somewhat successful in doing battle with indifferent city workers. Letters to the city government appear to get answered and they are answered more promptly. Phone calls usually receive some courteous response, although the "hold" button and "Sorry, that's not our department" are still in use.

Coupled with the mayor's accomplishments, however, have been some problems. Mr. Barry has yet to set an agenda for his administration. During his first months in office, when he had the attention of most of the city and the good will of the press, the mayor failed to pinpoint major issues for his government to address. He has not taken advantage of the wealth of talent that the federal government brings to Washington, and he has not done much to bring together the rich and poor, black and white, businessmen and religious leaders -- the array of groups -- that could work together for the betterment of the whole city.

Another problem lies in the mayor's repeated attempts to separate himself from his own District government bureaucracy. He told a press conference the other day that he is "still fighting the system." the mayor, however, was elected to be the head of that system and to be responsible for it. He cannot expect to get away with pointing fingers at the bureaucracy for his District government's failings. The bureaucracy is his bureaucracy.

Neither can he afford to be defensiv e when one of his own programs -- The Mayor's Summer Jobs for Youth Program -- does not work. Denials of reports on the program's failures by congressional investigatiors and reporters do not solve the problem. It is thee same old "line" from politicians. People who took a "stand" with Marion Barry expect more of him. And although Marion Barry is still thought of as a man of the people, he cannot think it is all right for him to accept a special favor -- like a discount mortgage rate.

Despite these shortcomings, and a reluctance so far to address the problems of the city schools, Mr. Barry's first year leaves every reason for optimism. There seem to be more good people in the District Building with more good ideas. During his second year in office, the challenge will be to achieve real results -- such as the improved delivery of city services -- with the aid of those better people.