The iSlimCharger worked exactly as advertised, providing charges and syncing with a clip-on Shuffle just as well as the default Apple adapter. If we were to nitpick, the only real flaw with the iSlimCharger is that it might be too small--we could easily see misplacing it, or losing it in the folds of a laptop bag or luggage. Likewise, you'll want to keep the charger--and the Shuffle itself--away from any small children and pets, because they could be a possible choking hazard.
It's worth noting that the iSlimCharger isn't the first such minicharger for the Shuffle. A quick perusal of iLounge.com found the very similar Marware USB Travel Dock ($20), Incipio IncipioBud ($6), and Carrot Idea USB Flexible Dock ($10). While any of those will probably work just as well, the Monster may be easier to find at some retailers, and it's backed by a one year limited warranty.
The Monster iSlimCharger for iPod Shuffle lists for just $20. That's cheap, to be sure, but--given that the Shuffle itself sells for less than $80--we'd like to see the price dip closer to the $10 point found on some of the aforementioned competing models. Still, if you're an avid Shuffle user looking to cut the clutter when you're on the road--or have fewer cables on your desktop--the Monster iSlimCharger is an easy recommendation.