I use these boots for winter sea kayaking.They are the warmest I have yet found.
The gusset ensures that they are watertight to the top of the boot.
The full lengh zip makes putting on and off easier.
I have been usin g these for 10 years, a pair lasts 4-5 winters, Eventually the sole wears through,so lifetime depends on how much walking you do.
I leave them between use under an upturned kayak,usually pour warm water into them in a cold morning to warm them up before use.
If they get smelly I rinse them with sodium bicarbonate solution as used in fridges,it does them no harm.As for drying after use I never bother.