Description: "A new approach to the original Small Continents map, adding sprawling island chains and better continent generation."
I looked through the file and used a plugin to compare the code with the original Small Continents.
It looks like it's basically Small Continents with the IslandMaker code included and applied to GeneratePlotTypes. Nearly all other values are the same, except for sea levels.
Also, the "better continent generation" is basically supported by the lower sea levels it uses, for less snaky continents. The original Small Continents used a Normal sea level of 75% and a Low of 69%. This one uses 72% and 65%. Additionally, tectonic islands and island chains further reduce that a bit, for even more land. I don't think the island chains code overlaps and adds onto the existing land plots generated the same way tectonic islands do (which is also applied in this script, just like the original), they need space and are placed in water. Also, For reference, Continents uses a Normal of 72% and a Low of 67% and doesn't decrease further because it doesn't get tectonic islands or island chains applied. So, with this map script, you're getting a lot more land! Expect lots of hostile natives in the fog!
Nonetheless, it produces some nice results, and the extra islands create even more passageways to link the world for early exploration and contacts. Though, I think I would recommend using a low sea level, to avoid nearly all coastal settlements and excessive choke points which may cripple the tactical AI; and mountain chains just exacerbate the issue. It could even lead to a lot of frustrations with the player as you're shuffling units around. (1UPT needs space!

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Also, unlike the other "Plus" maps, this one doesn't push all the city-states away from the major civs to the outer, infertile areas of the map. They're all mixed-in like usual, which in my own opinion, is most ideal for balance.
EDIT: Actually, the Normal sea level setting seems adequate enough. One problem with the Low sea level setting on this is that it creates a lot of land. That's usually a good thing, but if you don't modify the resource settings as well, you'll have luxuries really spread thin. Also, on Low, you may want to increase the civ total by +2 and the city-states by +4, since there's going to be a lot more space.