The town is well-connected to the north and south by bus. The AXA bus line provides quite civilized transport at a reasonable price. There are also cheaper, rickety buses available, as well as the usual minibuses which hold up to 20 people - scary but cheap.
If coming from Mbeya, Tanzania be careful of well established scam artists selling fake bus tickets. One of the scam artists even has an office in the main transit area in Mbeya. He also has professional looking lists of prices, services, etc. He may even use a cell phone to check availability of seats for you. As of September 2008 there were no buses running from Mbeya to Mzuzu or any other town on the Malawi border.
Instead, to get to Mzuzu from Mbeya, take a minibus to the border town of Kyela, Tanzania. Then walk 5 to 10 minutes across the border to the Malawi side. After the border, it's necessary to get to the transit center of a small town called Karonga. There may be minibuses at the border, but they are infrequent. A taxi can be hired for about $15USD. Once in Karonga there will be minibuses headed to Mzuzu.
Swiftair operates scheduled flights from Lilongwe to Mzuzu and karonga on a twin engine, 2 crew beechcraft 1900 http://www.swiftairmalawi.com
Mzuzu is small and navigable on foot.
Other than typical African market goods, there's not a lot to buy here. It does, however, possess the most northern ATM's, good if you've just come from Tanzania or find yourself staying longer in Nkhata Bay than planned.
A-1 Restaurant - located on the street behind the main banks and groceries in a commercial strip. Certainly the best food in town with a menu focusing on Indian fare with some Chinese selections. Extensive choice of dishes that are generally quite good. Prices are fairly steep for Mzuzu, but very reasonable by western standards.
Obrigado Leisure Park - centrally placed with hideous red and yellow advertising for Celtel. Inside the fence you will find a beautiful garden with tables interspersed throughout. The food is typical Malawian restaurant fare, including nsima or rice with your choice of meats or relishes. A bit of a beer den at night, it seems.
There is also a pizzeria near the bus station on a side street serving decent thin crust pizzas cooked in a wood fired oven. It is run by an extremely entertaining couple named Paolo and Emanuelle. Next door is Paolo's trading post stocked with some western luxuries such as M&Ms and decent toilet paper.
Nkhata Bay is about an hour away by bus or pickup truck.