I cannot in good conscience recommend this to anyone who is NOT familiar with making and modifying model kits, so 3/5. The kit has a bad reputation for several very good reasons - If you want a cool and big RG kit, get the RG Sazabi instead. However if you are set on getting this and follow the video mentioned below, you CAN make this a better kit.
The 16cm tall (almost MG sized) 2016 Sinanju is an aesthetics-first and mechanics-second Real Grade kit, as the inner frame is based on the 2012 13cm tall RG Mk-II Gundam.
If it's not obvious, the Sinanju is significantly taller/bulkier/heavier and while the Mk-II inner frame is very good for its time, it was made for a comparatively small Gundam and does NOT do a good job of trying to support the Sinanju.
The kit cannot stand on its own without leaning forwards due to the heavy backpack, which sticks out backwards and leverages the back. Attached are two images, one of the finished model and the other is the inner frame of the torso, which is a stacked-high spindly mess of parts that carries all of the weight across multiple joints.
In order to mitigate this, it is my strongest recommendation to watch the video "Fixing the Sinanju" by JoesGunplaGarage on YT. He gives a brief explanation of the issues and how to fix the spine with minimum effort, using only a nipper, glue, the runners that the kit comes with and tungsten putty to weigh down the feet. I have followed the guide (minus the putty) and while it will still fall over backwards, at least the back doesn't crumple. With the putty, it should be a lot more stable.
Other issues include the knee-pads not staying on well (glue them on), the wrists/hands falling off (glue them on), the shield being very loose (glue on the adapter), the limbs and joints being a little sloppy (unfixable), poor articulation and some caution needed on the red glossy plastics due to them being brittle. They also scratch easily, so a Razer Balancer is recommended.
The kit comes with:
1 Shield - Attaches (poorly) to the shoulder plate and (poorly) to the lower arm - You don't *have* to glue on the holder, but it falls off easily.
1 Beam Rifle - Storable on the back but you have to take the scope off and have nowhere to put it, so it's pointless.
1 Grenade Launcher that attaches to rifle or shield - Has a break-open function.
2 Beam Axes storable on the inside of the shield and they can be connected together for a dual-beam-axe.
2 Beam Saber hilts - Must be stored separately from the model.
4 Beam Axe effect parts 2x short and 2x long
2 Beam effect parts attachable to hilts and also attachable to lower arms
1 "Full Frontal" 1/144 miniature
1 RG style sticker sheets with foil and decal stickers - I heavily recommend getting waterslide decals, since the sticker borders are VERY obvious on the red plastic.
1 base adapter to put the model on a base - Slides off easily, so consider pinning or gluing it on.
The strong suit of the model kit is that it looks good - It also looks good if you give it a matte clear coat, so if you don't like the 'kitchen plastic' look of the glossy red, you should consider that option. This is very much a 'set-it-and-forget-it' kit that is not friendly towards posing and forget about playing around with the functions, because pieces can and will fall off easily. It's not a full 'hand grenade' kit, but it's frustrating to handle.
It is fair to say that the RG Sinanju is one of the rare low points for Bandai, since this could have been a good model kit, had they made a full inner frame for it, instead of reusing a 4 years old MS-joint pre-mold inner frame. Usually when you get a "bad" Bandai kit, it's at least only bad compared to the usual standard, but this is very much a non-competent model kit just in general. If it can't stand, can't hold its stuff and can't pose properly, it's just not a good model.