Just to be clear, this review is about the GS305.
Coolblue collects the reviews for various models in the GS3xx series and shows them all at one of the products. So I read all reviews about PoE for the GS305 (which does not have PoE). Don't let that surprise you.
On topic: The GS305 is therefore the basic version in the GS3xx series; unmanaged and no PoE.
Just a simple switch in a solid metal housing. No (rickety) on/off switch on the back, as with its predecessor, the GS105. Only a power input for the supplied adapter. Totally fine.
The switch is used to split the network connection at the TV over various devices, such as Smart TV, Apple TV and Ziggo box. Since these devices are usually turned off, power consumption (besides quality) was the 2nd factor. Thanks to the new 802.3az standard "Energy Efficient Ethernet", this switch has a power consumption between 0.31 W (standby) and 2.15 W (max).