If it lagging in the affect that, you walk fowards... your moving fowards and you pop back where you first were, that is usally associated with a bad internet connect to the server, or that server\'s connection is bottled necked.
If other people seam to be jumping about, it can be both to do with your graphic card /computer not coping with the ammount of detail on screen at any given time or the new client is just buggy and the graphics wont run smoothly with a lot of details on screen, which may make it look like server is lagging connection wise as it can make your request messsed up. that or the server cant handle too many people in one area...
give it a few days, there are a few bugs in the client