A verdict on the Canon RF 24-105mm f/4-7.1 STM IS has to be a bit more varied than usual.
In absolute terms, it's clearly a sub-standard lens. Its native characteristics range from good to downright terrible. The miserable vignetting and distortions have to be seen to be believed. Conversely, the resolution is actually pretty decent - which is a bit of a pity because you just won't use this lens without auto-correction.
That being said - it is highly unlikely that you invest thousands into a high-megapixel camera and then just a few hundred on a cheap kit zoom lens. The pixel-level sharpness increases towards lower sensor resolutions and the vast majority of users have cameras featuring 20 to 30 megapixels (as of the time of this review). Within this context, the Canon RF 24-105mm f/4-7.1 STM IS makes much more sense. The 24mm setting will still not be perfect here but it's certainly usable.
However, it's still worth pointing out that this lens is underdesigned. If you allow for zooming any lens below its designed minimum focal length, you will end up with black corners because the image circle has reached its limits. And this is what happened here. This is actually not a 24-105mm lens but more like a 28-105mm. Probably few would have complained if Canon marketed it like that - and our final rating would have been substantially higher.
Coming back to the less philosophical thoughts - the mechanical quality of the lens is pretty good for a kit zoom lens. The used materials are of high quality. The (extending-)inner lens tube is a bit wobbly though and this seems to be a theme across Canon consumer-grade Canon lenses. The construction is also a bit simplified with its combined focus/control ring. However, that's perfectly fine within the scope of this lens. The STM AF is pretty quick (if you avoid spot AF) and the image stabilizer does a decent job. This is also needed regarding the very slow-speed nature of the lens.
Of course, everything in life is a compromise, and the RF 24-105mm f/4-7.1 STM IS is all about making it possible to a budget. However, if you can stretch it, you'd really be better off with the Canon RF 24-105mm f/4 USM L IS. While more expensive, it's just a better investment.
