Maelstrom is a classic game, perhaps overlooked in the past due to its' relatively realistic historical focus. Indeed, purely historical role playing games are a niche market, and although the Maelstrom core rulebook does contain a hint of fantasy (with the innovative magic rules), it is on the whole very much a historical RPG.
It's a shame Maelstrom isn't more widely known, the rules are simple, the setting colourful and when it was released (back in the 80's), the magic system was revolutionary.
With the release of the classic fantasy toolkit, Maelstrom may now become a little more widely known and used, broadening its' appeal to those who perhaps steer clear of historical games. In essence, the toolkit does what I suspect many Maelstrom GMs have pondered or attempted; turning Maelstrom into a fantasy RPG.
The supplement introduces the standard fantasy elements to the game, such as fantasy races (elves, dwarves and halflings), and the typical classes of classic dungeon delving games (fighters, thieves, assassins, wizards, paladins etc). The information is presented succinctly, and in a useable format, so that it can easily be used alongside the core rules. There's a monsters section which includes details for the 'usual suspects' of a fantasy RPG (goblins etc). Of note is the artwork, which is well executed and evocative of early fantasy RPGs.
The supplement is by no means perfect; there's no information on a fantasy setting for example, and an adventure would have been nice. However, for the price, I don't think there's really any cause to grumble.
In summary then, for a few dollars, euros or pounds, you get the essentials for creating fantasy scenarios using the splendid Maelstrom system.