The great thing about this travel detergent is that it allows you to pack less clothes for a trip. Also, your luggage gets lighter over time, since each day when you wash your clothes, you discard one packet of detergent. It's also very cheap at about 50 cent per pack.
For a trip, I'd also bring along some nylon rope to hang your clothes. No need to buy those expensive travel clothesline. Buy some plain nylon rope (non-colored) since the coloring from the rope can transfer onto your clothes when wet.
Btw, while on vacation, I recently tried to wash my clothes with just regular liquid body soap. Surprisingly it works pretty well. I might skip taking along the detergent packs next time and just use regular soap. This will save even more weight.
I tried to find these locally but couldn't, so I ordered them online from Amazon. These are great for travel; the thick pouches mean that they won't leak or accidentally puncture, and they are great for hand washing in the sink if you dilute the soap and only use a small amount. Since this comes with 20, I know they'll last a few years.