C.L Werner evidently has little experience with elves, and the elven parts suffered as a result.
I thought this was a brilliant novella (as are all of the Storm of Magic novellas) - though it's a few months since I read it.
I am not sure whether when you say 'rushed' you just mean the story had too quick a pace or that the writing was rushed too. The former can be said of many novellas, but I don't believe the latter is true. If it was of a quick pace, I personally did not find it cluttered or confusing - I would argue, if you have read them, that the others two Storm of Magic are more 'rushed'.
I am not convinced that the ending was rushed to either. Although I would agree that the finale - the set piece - had little to it. This may be the opposite of what you say.
I completely disagree with the comment that characterisation was lacking. I thought, with the skaven in particular, the characters were clear, distinct and interesting.
I think it's perhaps wrong to see the Wood Elf as the main character. Werner often has the villain as the main character and it was evident in this piece that the Skaven necromancer and Grey Seer were the the leads. I think it's a credit to the author that he didn't settle with the Wood Elves as cardboard good guys and he developed them some way. Werner went a different way with the Elves than what I would consider to be the typical Wood Elf, but I didn't see anything that could be construed as a mishandling of them.
I am not sure I agree that the enemy at the conclusion came out of nowhere. There were a number of subtle references that something sinister was going on.
I do agree that the earlier politicking was probably the best of it with the eventualy uneasy alliance.
I was sure whether your overall rating of the book equated to your criticisms - what is your scale? what's a 1/10 for you and a 5/10?