first of all great job on the photoshopping... looks spectacular !!! i also have respect for announcing such a simple set as your first MOC. what a great idea. it shows that MOCs don't have to be multiple thousands of pieces (as seen on classic-castle) to be great.
i look at this set as if LEGO had officially released it. i used all the same criteria when rating this MOC as i do when i rate LEGOs sets. as i said before small sets are great, but they have to present something new, that the larger sets just cant do. for example, the "cargo train" has great road cars. but they get lost behind the shadow of the overpowering train its self. within little sets, the focus is not driven from the smaller objects... all-in-all i think the smaller MOCs are harder to produce and to make look great. all the smaller details are revealed, and their construction has to be just right, with exactly the right pieces. for example you can't use two 1x2 bricks in place of single 1x4 brick. in a larger MOC you can get away with it !!!
this set is simply men, and as with the "frontier patrol" of the western series i would give it a low score due to its lack of creatively of putting bricks together, and for not bringing anything new to the table that a larger set hasn't done. notably, the cannon cart does have handles, and that separates it from the cannon cart in imperial trading post. this MOC is a more of a tribute to LEGOs great craftsmanship of designing mini-figs, and not to the actual design of the set.
it is interesting to note that you decided to add a horse... it could be argued that you strayed to far from the "pirate" theme, if you are trying to produce a set in the style of LEGO releases. LEGO used boats as modes of transportation for the pirate sets. this possibly could be attributed to the fact that they need to keep some distance from the castle theme. although i am not objected to adding a horse to LEGOs pirate theme, personally, i would never add one when trying to keep to LEGOs consistency with the theme.
i am also interested in this idea of creating rules and limitations with my MOCs. this also helps when mixing MOCs with LEGO releases.... and as you said its fun to explore the ideas the LEGO missed. as soon as i get a digital camera i'll try to post some of my MOCs which explore this concept.
i gave your MOC a 2 of 5, and don't take that hard, i think this is a beautiful group of images. you did a wonderful job and i would love to see more !!! i would even venture to say that these are the best MOC images i have seen yet !!! again, great job in photohop.
i am thankful that there is another LEGO fan that holds ideologies similar to mine. and even though i frequented this board several times, it took this post before i signed on and started contributing - brick miner