Poker... deal me in.
The color of the legend text against that background is absolutely hideous. Maybe it's my laptop monitor, but I can't even focus on it - I will assume the legend is a work in progress.
Best hand gains bonus - best hand per player I assume. It should probably say that even though to do otherwise would be impossible to code (but how many players know that?). Brilliant solution to the age-old problem of how to assign bonuses to a deck of cards.
No other bonuses - does that mean no automatic three reinforcement armies per turn? Ah, I see by your first post that it does. Again, more clarification needed, because I don't think of the reinforcements as "bonuses."
Legend clarity is going to be of great importance on this map. I don't think it would a bad idea to somewhere show the rank of the cards in a deck, 2 through A, for any players who have been living under a rock and have never seen a western deck of cards. Maybe down the right side of the legend? And example representations of the hands might help out as well.
Chances are many players will start with at least a pair, since there are so many different ways to hold one. Thus I think the +3 is a bit steep, because it gives advantages to the players who get their turns early. If I go fifth, four players have had a drop of three armies each to pummel me and anybody who goes after me, leaving us with an initial bonus of only one and I'm done. I think I'd play with bonuses to make the beginning of the game more equitable - maybe give everybody a minumum of three, plus a fourth army for holding a pair, five for two pair, etc. What's more, everybody is used to starting a turn with three armies... you'll be getting some nasty PMs about this map when players start their turns with 1!
Another thought - what if everybody also got a +1 auto-placement on their highest card? you could work that out in the XML with 52 bonus regions, each of which overrides the card a value below it. Though I guess you'd need to rank the suits as well... hmmm... maybe not scrap that idea.
You've got a world of hurt on your hands in terms of where to put all the cards, because this could so easily lead to frustrating play. I think you need to consciously set up some easy pairs so players can try to plant themselves up in a sector of the map and set up some borders. For instance, right now I like the top left corner, because you can grab a pair of twos, expand to make it three twos, then grab another queen for a full house; six contiguous cards give you a +8. Not sure if every corner has the same advantage.
Finally, this map needs space. While I think wording of the legend is vital, it would be nice if you could push out the space provided to the cards to make it very easy to identifyt he bottlenecks and key connections.
Whew... I think your work is cut out for you here Yeti!