I am a huge fan of the "Arthurian" era (Saxon invasions of 5th-6th century Britain and the efforts of the Post-Roman Britons to defend their land). Ever since I first saw these rules, I was intrigued, but the cost put me off. When they went on sale, I had to pick them up.
Figures are mounted individually but formed into units of 4-6 figures. An army runs about 40 figures, but each figure represents one man. Thus, these model large skirmishes. I like scale, although I may reduce the unit size by half.
The major turn-off for me is that they use a card-activation system. In some games (e.g Memoir '44), I like card activation but I am not sure how it will work for solo play. I bought the PDF edition of the game, so I am not keen on having to make my own cards.
A huge bonus is that the campaign system looks FANTASTIC. A player is either a Saxon raider or British defender. The Saxon is trying to conquer the British kingdom, but first he must build up his wealth and power by raiding the Britons. When he is strong enough, he may launch a conquest of the kingdom. Meanwhile, the Briton is trying to build up his prestige and wealth in order to stymie the invaders. The system seems to really give the flavor of the period.
I originally mentioned that I was looking for fantasy skirmish rules, so what would I do with a historical rules set? Not to worry, it seems that Dux Brit is convertible to different periods and even fantasy realms (at least those that are relatively realistic). There are at least a couple of bloggers (example) planning to use the campaign system for war games in Game of Thrones' Westeros. I may use it for a fantasy Imagi-nation.