Al Khan is the part of Sharjah I'd point someone to first. The lagoon and the corniche change the feel of the place, people are out walking in the evenings and the beach is a few minutes away rather than a weekend trip. Having the Aquarium, the Maritime Museum and Maraya Art Centre inside the neighbourhood is unusual for a residential area. Al Ittihad Road gets you into Dubai quickly when the timing is right.
Housing is a wide mix. Maryam Island and the newer towers are well finished with real sea views; some of the older buildings are dated and worth viewing in person before you commit. Peak traffic on Al Ittihad is the main gripe, and parking at the older towers is tight. Good value for waterfront living otherwise.