A very entertaining and fun mission. I really enjoyed playing it. There are several strategies to try out here, it would be a good challenge for a newbie player. I won using a very simple and -probably- the most effective tactic in the mission. I've forced together my archers and slingers, and then sent them under the south-western tower, in a few minutes they have cleared the area. After it I've sent my rams to break the wall and my knight to break in the very weak inner wall's weakest part. Then I've sent in my 135 spearmen and voiala: WIN!
The mission has many ways to siege the castle, but my strategy worked here too good and the mission was very easy in that way. And the enemy castle was too weak.
Not a bad scenario, the idea is good, you just need to expand your imagination better and your maps will be much better in both categories.
Map Design: 2.5
Not a good design, the map lookes very rushed and the castle also looks a bit weirs and ugly, you should try harder in maps design. Anyway I don't judge you harshly, as this is only your third map.
No story, not even instructions, you have a whole page for your desription. Use it! ;)