After seeing a few advertisements for these things, I was immediately intrigued ... while Arby's could have easily done the gimmick of releasing just plain roast beef on slider buns, they actually added new things to two of them! (Actually four... there are six Mighty Minis total: Roast beef/turkey, spicy roast beef/turkey, and crispy onion roast beef/turkey)
Alright, so basically these minis are two slider buns that are still connected with roast beef (or turkey) and whatever other toppings, depending on which you got. The problem with this is that they lay the roast beef across both buns, so it's hard to rip them apart cleanly. More impractical is trying to eat both while they're still together, as if it's a mini sub. Either way you do it, it'll be sort of messy... I'd have rather Arby's just released a full-sized sandwich instead of trying to make the minis.
Crispy Onion: This one's pretty uninteresting, but it's not awful. Simply, it's roast beef with crispy onions on top. Not fresh ones, but rather ones that are out of a bag or can. They don't taste bad, but it's basically like those French's onions that come outta the can... just a little bit better. The sauce they put on is apparently "Au jus spread", but I really didn't find that it added much different flavor that wasn't already there from the combination of the roast beef and the onions. Not bad at all, but rather average. 3.5/5
Spicy: Saving the better one for last, this one was pretty tasty and more interesting. This one has roast beef (or turkey, whichever you choose) with pepper jack cheese and roasted red jalapeno ranch sauce. Sound better? It should, because it is. Personally, I'd've only liked this more if they put the crispy onions from the other one on here. The ranch sauce that they use is actually surprisingly good, and has a decent amount of heat -- it won't make your nose run or your eyes water, but it's noticeable. Would get again. 4.25/5
As I said, there's also a plain roast beef or turkey Mighty Minis selection, but that's no fun. The only difference between those and their big brother sizes is that the bread used for the Mighty Minis is different. It doesn't taste different, but it definitely has a chewier texture. The Mighty Minis from Arby's are pretty yummy (the spicy one in particular), but they're difficult to eat without being messy. Either you somehow rip them in half (not an easy task without having the meat slip out), or try eating it like an elongated roast beef sandwich. If you have a knife, use it ... it'll make your life easier, and cleaner. I hope Arby's considers keeping them around.