I was a child of the arcade era. Sneak off and walk up to the mall to waste quarters on the arcade cabinets, all that jazz...
And this just brought back tons of memories. All the quarters I dumped into this thing since I had no clue how D&D worked. That's the thing to remember going in.
A side-scrolling brawler incorporating D&D mechanics, one would be surprised at the amount of knowledge they should have going in. If someone doesn't have a party when they're a magic user, they might wonder why they can't cast their spells against the Beholder boss. Or in Tower of Doom, they might wonder why certain monsters just won't stay down until they're burned or beaten to jelly.
Even not having this knowledge however, these games are still fun. Replayability is definitely a factor, with dozens of items to collect as you go along. A radial item wheel is available to access the items or spells you collect, and even to switch equipment for classes that can do so, and while some people may claim the keyboard controls are clunky it's a minor hiccup in all honestly. Even going from WASD movement to arrow movement for this isn't the end of the world. The game isn't as pretty as one would expect from a packaged port like this. I personally haven't tinkered with options, but there are some glaring issues here and there with things that just pop out, at the least in Shadow of Mystara. The audio is just as I remember, excellent music for around the year these games came out and a reminder that before Squenix took over, Capcom was the go-to music company.
Considering you're picking up two games for the price of one, the TL;DR of this is yes. Chronicles of Mystara is worth it. Graphically, you get what the age and port would expect. Audibly, the game is ear-candy. Playability-wise, exceptional. It's not perfection, but it's damn close to it for the price.