If you want a versatile all-in-one zoom lens, can check the 18-200. If you want a high quality EF-S lenses then you can look at the 15-85 or 17-55. Both are great lens, but you get f/2.8 with the 17-55.
Without stating the purpose (which needs some more details from you) it is not possible to declare any lens 'very useful'. But most cameras come with kit lenses for a good reason. Wouldn't it be quite strange if this lens were not at least 'useful' for those people getting their first DSLR cam?