Accessories for the Stuart are amazing. You can get a realistic 37mm gun barrel and more appropriate .30 cal hull barrels and better turret .30 cal or mount a .50 cal. You can add, gas cans, tow cables, ammo cases. Just anything your heart or pocket book desires.
Oh, I forget, of course, after you paint and weather it, you can add decals.
I just got a bunch of Amorex accessories, all metal and works of art....tow hooks, tow cable, .30 cal barrels and lift rings for the turret.
The 21c sound effects are excellent, very close to the real thing, speed and turning is very close to a scalled down actual Stuart. Not like the reported very high speed of the Abrams. I initially had trouble with the track slipping off the boggies when I ran over twigs, but it straightened itself out after repeated uses. No other problems but I don't run it in water or up sand dunes.
You mentioned the added figures, I wouldn't count on using the four, two are General Patton and his Colonel (from the latest 21c Patton Jeep) and the other two are the Germans from the 21c Kubel. The Colonel is the one with the moronic grin.
One word, great describes it. If you are a nit picker, you can accessorize to your hearts content, or keep it as is

. Keep you eye on eBay and you can get one decently priced if you are patient.
A word on being patient, my first 1/6 item was a customized 21c WSC and I've been looking for an untouched one for two years, but prices are insane. Recently an eBay listing for a Scout Car poped up with a "buy it now" figure of $67, brand new, never been out of the box. Scout Cars go for $250 to well over $300. It lasted on eBay for about five minutes before one of the gentlemen on this board snapped it up and knowing I have been looking gave it to me for his cost and his shipping.
It never ceases to amaze me what a great bunch of guys are on this board and what a great product 21c produces.
TTT
Sometimes I am the windshield, sometimes, I am the bug.