METRO'S RED LINE introduces itself to Silver Spring today - and vice versa. There were free rides on Friday, but today the new rail line gets down to the serious business of carrying people to work. Having consulted with some of those who command some months' experience with subway travel, downtown and on the line out to Virginia, we can offer a few views about the service so far.

Today's new customers in Montgomery County, Takoma Park and the neighborhoods of nearby Northeast Washington are not likely to go through the epidemic of breakdowns and delays that visited the Blue Line last summer. One reason is that Metro's police are gaining competence in running the new system. Another is that the cars have already been in operation for some time on the older section of the line.

The real jolt will come in two weeks, when the bus lines along that corridor are reorganized - and sharply curtailed. As in any revolution, there will be winners and losers. If you have had easy access to a convenient express bus, you are likely to find that it turns into a pumpkin, like Cinderella's coach-and-six, on Feb. 20. the substitute that Metro has in mind for you will probably be a local bus to the rail station, then an annoying transfer to the train. But if you have good access to a rail station at either end of your trip, you are likely to find the trip easier.

The whole Farecard procedure is a pain, and you will probably wish that Metro would just let you throw money in a slot and be done with it. You will get used to the card shortly - but keep it in mind that there will come a day when you find yourself at a station with only one gate working, and that one is being used by a kindergarden class on its way to the museum. ("No, Georgie, hold the card the other way, dear.") In the background there is always the ding-dong of a train - departing. In our society it is considered coarse to push little children aside. But if you try to step through a dead gate, the vigilant Metro official will seize you and drag you off to answer for your crime.

The trains aren't terribly fast, They seem to run consistently more slowly than the speeds originally advertised. But they are safe, very clean and remarkably comfortable. That turns out to be the surprise: the comfort of the rail cars. The seats are a little bigger than those in the buses. The air conditioning in summer is reliable, in this season, the cars are well ventilated and do not get steamy like buses. Unlike buses - and taxis, cars and bikes - the rail system is snowproof.

Advice to beginners: Try to get Farecard befor your first morning rush. Consider taking the cars at the end of the train; if there should be an occasional unexplained stop between stations, you'll hardly notice. Leave yourself a little extra time, particularly in the early weeks of operation. But try it. It turns out to be a very pleasant way to move around town.