Thanks G1. That photo is helpful.Here's a link to a photo in a previous post that shows the one in our 2014 Limited FWD: Must have accessories for Sienna
The main benefit is that it holds drinks for the 2nd row passenger better than the holders in the sliding doors. As shown in the photo, we have an ice bucket that fits perfectly in the space when the rear portion of the console is slid all the way to the rear. When the ice bucket is not there, I use the space to hold a bunch of shopping bags. I can't think of any drawbacks. It's handy but I doubt that I would miss it if I had never had it.
There are two versions of the "pocket, console box" on the back of the sliding console - one with the video and 120V plugs and one without. I assume that the one with the plugs is for the Limited Premium FWD with the rear video screen and the one without the plugs is for the "regular" Limited FWD.My non-sliding console has some electrical plugs, so this may be a non-starter unless there is a similar version of the Limited console that both slides and has the plugs.