To get one thing out of the way first, these are some of the weirdest armies I have ever seen.
The plot for the show can be summed up pretty quickly. G.I Joe are the good guys, Cobra are the bad guys. The plot overall revolves around Cobra wanting to concur the world with some sort of super weapon, and its up to G.I Joe to stop them. Remember, this is the time period for cartoons where the priority wasn't making quality entertainment, it was selling more toys... the original time at least, even though that trend never really died... Point being, the story is pretty basic overall with plot really coming from the episode to episode story, there's no real continuity except for multipart episodes (which the show opens with two 5 part specials). Best thing I can compare it to is Generation One Transformers, where the overarching story wasn't a thing overall.
Another strong comparison to Generation One Transformers is in the characters and technology, as stories had to revolve around selling toys. But that's kinda where that "weirdest armies" line from before comes from. Granted, I'm assuming the hardware is faithful to the toys, but the military equipment for both the Joes and Cobra look really stupid seeing as they're supposed to be "realistic" (kinda) for the time, in terms of the show. The vehicles do however have a level of charm to them, and look like they're animated versions of the toys, including cockpit windows being the point of entry for the pilots, and tanks with exposed drivers. As for the characters... you know how most depictions of armies have one or two key figures and then the rest are nameless grunts? Well while that's more of an issue for the Cobra grunts, it seems like they tried to give personalities to all of the Joes and... who uses spears and a crossbow in a modern day army? Who names themselves (I hope it wasn't there parents) Sergent Slaughter, Shipwrecked, Spirit, ect. Granted those names sound awesome, but its where I'd kinda like the setting to be more futuristic then modern day, separate it a bit more.
I think the constant comparisons to Transformers Generation One is actually the main reason why I find myself really liking the show. Animation and soundtrack is similar to G1 Transformers, and the stupidity of some of the plots have a weird charm to them. Is it good? No, there are genuine flaws here which will boil down to "Can you accept a cartoon that exists to sell toys?" If you can and you're looking for a show that's 100% army themed without making it depressing or realistic, then you'll like the show. If not though, then trust me, stay away. You'll save yourself a headache. From one army glorifier to the next. Come Sunday... ugh... I'll be tackling Transformers: The Last Knight.