I like the Sea to Summit tarp ponchos and have used them for years. Beside standard 'poncho' use, they also can be configured into a tent-like shelter by using your trekking poles (Yes, I know that's not a big feature on the Camino but I use my gear for many of uses too ). Once you learn 'the dance' required to easily put it on, it a great lightweight item that takes up very little room in your pack.
I can't give enough praise to the Altus Poncho.
The Altus Poncho is durable and long (I'm over 6 foot).
It snaps up the front, which allows for ventilation.
When walking, a big decision you must make is... when to put on your rain gear.
This requires that you stop, remove your Pack, put on the Coat/Jacket, and put the Pack back on.
This is OK for clearly defined storms. It is useless for off-and-on drizzle (in Spanish that is pronounced Galicia). Taking the Coat/Jacket off/on is time consuming.
Typical (American) Poncho
This is closed in the front. No ventilation. Great for standing in the Rain, not for walking.
It is a bit pricey. It is available in SJPdP, but should be preOrdered.
It has room for a full Pack and has three snaps to minimize it, when not required... like after arriving at an Albergue.
It has a row of snap in the front. Opening can help with ventilation.
It's big feature is.... You're walking in the off-n-on drizzle of Galicia. When the rain stops, you open it up, take out your arms, and let it hang from your Pack (Like the Hunchback of Notre Dame wearing a Superman cape). If it is windy, you tie the poncho-arms around your chest.
When the rain starts again... you slip in your arms and do up the snaps. Waterproof again. Quick, easy, no stopping.
So.... three choices
1 Fully closed
2 All open
3 Hang from Pack
A Very Popular misconception........ A Rain Coat Keep You Dry!
They do not!
Rain Coat's give you a choice....
1)Leave it OFF and get wet from Rain.
2)Put it ON and get wet from Sweating.
This is why ventilation is soooo important.
On the Camino, your walking up a hill, with a full Pack, in the rain. You will sweat.
I can remember, one Drizzly day, walking on the Camino like a Zombie... arm straight in front of me.
I was walking into the wind/rain and my Altus Poncho sleeves (unsnapped). They where catching the wind and cooling (drying?) my arms and torso.
(another time) I was walking across the Meseta, it was on and off rain and a 50 to 80 Kph wind. The Pilgrims with the simple Ponchos, with side snaps, looked like they were wearing a plastic flag that was tied to their necks. Their Ponchos had failed.
The Altus Poncho is also durable. A couple of times I went off trail to take a Picture. My Poncho got snagged. One time, it did tear (an inch long), considering the barb-wire and tug I felt... that wasn't bad.
If you check the picture of us (on the left of the page) we are in Galicia and wearing our Altus Ponchos.