Critically Taped - On outerwear with critically taped seams you only have taping at the key points where potential leakage can occur. This is acceptable, or even advantageous if you live in a dry climate, if you're more concerned with breathability than dealing with wet weather then outerwear featuring critically taped seams is the way to go.
Polyester Fill - Polyester insulation may not be as warm or light as down, but it's far easier to clean and performs better in wet conditions. If cost is a concern or you live in a wet climate then polyester insulation might be your best option.
Synthetic insulation is measured in grams, so a jacket with a 80g rating simply means that a 1 meter by 1 meter piece of that particular jacket's insulation weighs 80 grams. The higher the rating, the warmer the outerwear.