This is a passive attenuator which does not alter the guitar's tone unlike active attenuators do.
It is very simple and easy to use and the minimal features may also preserve the guitar's tone, just like a simple guitar amp when compared to a more complex amp.
Also, it can attenuate up to 200W of power (for 8 ohm cabinets) which is one of the most powerful I've come across on the market.
I was considering getting an other type of attenuator which uses a speaker motor and is said to be even more transparent on tone but SPL's professional site and informative video demos on YouTube convinced me to make the choice to get this attenuator instead.
I also want to mention that SPL have a very helpful service and will answer all your questions.
Personally, I will order a second copy of this model because I have two cabinets. I could use one attenuator for both but two would handle the power more easily and the amplifier's master volume could be set higher, allowing for more power tube tone and even saturation, if desired.
As for features, it's all on the item info page; for example, variable resistance for use with different amps and the text at the back is printed both upright and inverted, for easy reading when it is connected and you want to read the connection info! Very good idea!