Before I get into the review let's just get it out of the way---steel combloc mags are the standard for a reason: they're fantastic reliable/durable mags. Ok, moving on...
I always avoided US Palm mags for two big reasons; steel mags were dirt cheap and great and US Palm mags had some serious issues when they first came out (the so called Gen1 mags) and didn't seem to live up to the claims about their product.
I got a US Palm Gen2 mag in a trade and used it off and on at the range and noticed it ran great, took abuse well, and performed well in general. Then, I saw a site selling them for $18 shipped at the same time steel mags were going for $12-15 most places. I took a shot and ordered a bunch of them to add some more depth to my box o' mags. Here's what I've found with the batch:
-They've been 100% reliable thus far through thousands of rounds in several guns.
-They're lightweight (7oz vs ~12oz for most steel mags).
-The price continues to drop. Several sites are selling them for under $25 shipped currently.
-Steel mag prices continue to go up; especially after the election.
-Several colors are available.
-I've left mine loaded for several months with no issues to date.
-Steel cage around the entire top of the mag to include lugs (not in the lips though) seems pretty strong (as demonstrated by the AK pushups in the video below).
-They lock up tight in my AKs with little to no wobble.
-They're US parts for 922r compliance.
-Cost. Although the costs are going down, they're still more expensive than the proven steel surplus mags.
-Customer service. I emailed and called them several times with questions about the design and they never responded to either form of communication.
-Reputation. As mentioned earlier, their Gen1 mags had issues and they didn't live up to the claims they made at the time as proven by people cutting their mags in half and not finding steel where it was supposed to be. It seems they've rectified this but that leaves a bad taste in a lot of peoples' mouths.
-No steel in the feed lips. It hasn't been a problem yet but given the choice I'd prefer it.
-They're wider than a lot of steel mags and may not fit in combloc mag pouches.
Here's a video showing the mags in several AKs, a drop test, a size comparison with a few other AK mags, and of course a bunch of shooting: