I think this is a solid entry in the line. I like the graceful pose and gentle but powerful feel of the piece. I don't have problems with the paint job or the hair falling down in front of the ears. I just think that this is the first character in the line so far that is not a member of the Fellowship, and therefore doesn't feel as essential.
I can understand collectors passing on Arwen because she is a supporting/minor character (particularly in the books), and some need to pick and choose their maquettes based on desirability and Arwen just might not seem like a character that every fan is just dying to own. But I do think this is a quality piece. It's a bit too bad that she came the day after Gimli, because Gimli is fantastic and one of the best (maybe the best) of the line so far. But Arwen doesn't get me as excited as a character, although I am glad I purchased this and she looks great alongside Aragorn.
She will probably be the least appreciated maquette for a while, but I hope that's because she is a minor character and not because of any perceived lack of quality in the piece itself. Sideshow did a great job with Arwen--but in the end, it's still Arwen. So your feelings and enthusiasm about the character will impact your desire to own the maquette. I do like that the line will not just feature warriors in dynamic poses, but also make room for pieces like this. I can imagine a more thoughtful pose working well for someone like Faramir, etc. Arwen is actually a nice contrast to Gimli, who is at the other end of the spectrum when it comes to dynamic action poses. Aragorn and Arwen make a nice pair and they are worth owning. As a hopeful completist in this line, I am happy to have Arwen in my collection. Even if she ranks fifth out of the five released so far, I'm still 100% glad to have her as a little something different to round out the line. It just leaves me looking forward to Boromir!
Oh, and hooray for number nine!!! Many people will tell you that numbers don't matter, but I still jump up and down when I see a low number come in. Can't explain why.