this is a very durable and versatile sleeping bag, having used it a white out in Switzerland and throughout the year in the UK. somehow it manages to regulate your temperature very well despite having a filling with incredible lofting capabilities, i have never had an uncomfortably hot night in it. The zip is great as its dead easy to use with numb or cold hands although it does have a tendency to get caught on the helium fabric which is a bit annoying. The built in velcro closed neck seal is excellent and really does keep the heat in if you roll about in the night however the orange elastic drawcord on it can dig into your neck and be uncomfortable. In terms of weight, i cant think of another bag with a better trade off between weight,material and fill, size wise the compression sack supplied has no compression straps to squash it down which is unfortunate as the bag does take up more room than others in a pack. The down fill is excellent in terms of heat retention however it does require specialist cleaning othwerwise the down will become less effective when its dirty, which if used a lot it can be regular and expensive. I have found the colour to be a big plus point as it contrasts well against most environments making it both easy to find when making/breaking camp and a very good emergency panel marker for rescue teams.