It was a four hour delay, but given the conditions I'm fine with them making the safety call. The amount of logistics that go into making regular passenger flights happen in Arctic conditions is amazing - at Oslo, where it was sub-zero and snowing the entire time, a fleet of vehicles continuously clears the runway of snow, and every departing plane is leaped on by four specialised trucks that shower every important surface with de-icing fluid.
Taxiing round Oslo, you just see endless expanses of snow, and entire groups of aircraft completely iced over as they've been sitting there for more than a few days. The fact that it's possible, let alone economical, to run regular passenger flights with full-size Boeing 737s in those conditions is amazing.
Norwegian also hits above its weight for an ostensibly low-cost airline - most of my flights had free WiFi on board, the seats weren't ridiculously close together, and the cabin crew were very friendly. They're introducing more transatlantic flights this year, too, including two routes to San Francisco, which should be interesting to watch.
Tromsø is actually a relatively big place, and as it as no trains or trams, road transport is essential to getting around.
As I was planning to drive outside the city and see some of the surrounding countryside, I opted to rent a car (most major car rental companies are represented at the airport, even if they only have about 4 cars each), but there's quite good local buses and, of course, taxis.
The taxis are, like most things in Norway, really quite expensive - the base fare is something like 80 NOK (£8 / $13), and for a journey of just over a mile I paid 140 NOK. That said, they're all metered and incredibly friendly, which is more than I can say for some cities' taxis.
If you are renting a car in winter, it's very likely that it'll come winterised (snow tyres, lower viscosity oil, etc.), but it's worth checking. Driving on snow and ice is also trickier than you might expect - make sure you take it slow and allow plenty of time to decelerate.
The roads in Troms county were all well-cleared and generally had only a thin layer of packed snow on them, if anything - it was a relatively easy driving experience. That said, never approach winter driving lightly; always carry warm clothes, food and drink, and make sure the car is in full working order before you depart.