Summary: Good, solid, very similar characteristics to rattan. Probably will out-last your rattan sticks.
Got some new polypropylene sticks from manventureoutpost.com. I had a friend, Jeremy Michael Jones, who also practices Kali recommend I get them. They're 32" in length and 1" in diameter, manufactured by Cold Steel. I've taken some photos of them next to other weapons so you can compare visually. From the description:
Heavy. Heavier than my rattan ones. Not surprising given that many natural woody materials have a very high strength-to-weight ratio. Even my 1 1/2" diameter rattan sticks are lighter than these and these new ones that are only 1" diameter. To me this is both an advantage and a disadvantage.
Good quality. They feel solid, sturdy, etc. In the photo you may notice that they look like they're put together in sections, but they are one solid piece. I think the sections are for grip and visual purposes.
Read the rest of the post here on The Martial Explorer.