Over the last ten years (since I have been making regular Tibet visits) I have seen that conditions and opportunities in Tibet are constantly in flux.  In the last two years,  China's efforts to develop Tibet as a Tourist destination  have materialized, especially since the arrival of the new train.
          Most tourists are on an itinerary that takes them only to the two large cities, and, then, only to the most well known attractions.  Therefore,  in order to see Tibet and learn about Tibetan culture, it is best to go with a guide who knows the area, knows the country's geography, and knows how to avoid the ordinary tourist routes.  Tibet is still magical.  There are untouched areas and infrequently visited areas that are phenomenal.  The shamans, the cave dwellers, the early Buddhist and Bonpo sites with high lakes and peaks are still there in all their glory.  After June, Tibet will undoubtedly be open for travel and there are solid reasons why this may be the best time to go, including downsizing of  mainstream tourism, and it is an important time to connect with the people.
          In choosing a tour at this time (assuming you find one that is not cancelled) you may want to think about the sensitivities of your leader, whether money will spent in beneficial ways, whether the environment and people will be respected. Yes, it is still very much worth visiting Tibet.  But choose your leader, agent, and plan, carefully.    Lynnela