I didn't mention trunk space because the OP didn't mention trunk space as a factor in his decision. The Corolla has 12.3 cu. ft. trunk volume. The Prius has 14.4 cu. ft. The Camry has 14.5 cu. ft
Of course, the shape of the trunk is just as important as cubic feet, but it appears as if the Prius is pretty close to the Camry in trunk space.
Why are the batteries so long life and what
The batteries are nickel metal hydride.
The batteries have a long life because the charging control system keeps the batteries' state of charge in an optimal range without ever depleting the batteries or charging them to 100%. NiMH batteries in consumer electronics have a much shorter useful life span because the range of charging and discharging is much greater.
The batteries are just as reliable in very cold climates.
-25 temp reduces its capacity but doesn't eliminate it. In other words, you're still ahead, but not as much as in a warmer climate.
Salt may raise one's blood pressure, but in hybrid Toyotas, the battery packs are not exposed to road salt since they are in the vehicle's interior.
I don't plan on buying a Prius because I don't need a new car right now. I would consider a hybrid Highlander or RX 400h when it is time to replace our Sequoia after we are empty-nesters.
My sister has a 400h and likes it.
Toyota plans on eventually offering a hybrid version of all of its vehicles. The limiting factor is the capacity of the plants that produce the batteries. Toyota recently announced that it is building 3 new plants to produce batteries.