Rating: 4 / 5
These poles suffered (and maybe still do) from some quality control issues, but once fixed are solid and reliable--and can be an excellent bargain if you take advantage of these problems...
First, the insides of the poles are too slippery to grip the duo-lock mechanism reliably. When new, the fix is to slide the poles almost apart, then tighten them--the locks will grip at the ends of the poles. Then, don't loosen them too much--there should always be a "drag" on the sections when adjusting them. After awhile, the poles seem to "break in" and this becomes less and less necessary.
Second, many poles had glue problems--either with the tips or where the locking or shock mechanisms are inserted into the pole. The fix is easy--clean out the contact areas with alcohol--both surfaces--then use epoxy to glue the pieces back together. (In a pinch, "superglue" can work if the surfaces mate well...)
I suspect that both these problems are related--perhaps some residue remains on the inside of the poles after they are made, preventing the glue from sticking and the locks from locking. Once this residue is gone, they function as designed.
Now, why would you buy a pole with these problems? Once the initial defects are fixed, the poles are solid and reliable, and if you got them new, they have REI's implicit lifetime warranty anyway. For those looking for a deal, there's another option: due to REI's generous policy, a number of these poles are returned, and they can be purchased by members at one of the REI "garage sales" for a fraction of the new price--usually $20-$40/pair. Many of these returns are in as-new condition--they just never locked, or they came apart immediately. On the other hand, products purchased at the REI "garage sales" don't qualify for the lifetime return privileges (they put X's on the products using an alcohol-soluble ink so they know they were returned already...)