Well first of all hello there and welcome to 40konline^^ let's get started
I think you can build a descent army just because you have a wraithknight in here
If you Haven't bought the codex yet let me suggest you to wait until mai as a new one is underway.
If you look around you will see that wraith list aren't that uncommon, and they are fairly competitive in friendly environment. This box is very good fluff wise as the number if each units is pretty nicely caculated. So that it make sense in the fluff. You will have a lack in mobility and no hq choice in this box. So i would suggest a few things to get with this.
1 Get spiritseer, it's a pretty descent hq choice not too expensive and work very well with wraithlist game wise and fluff wise.
2 concider buying some mobility team. The biggest flows of wraithlist is the fact that they are fairly slow, with the Iyanden suplement that's not really true, but same as before if not bought already wait for the new codex in mai. So gor mobility i would suggest some warp spider, if they stay as they are now, in the new dex, they are going to be deadly efficient, so keep that under your arm, or if you don't like warp spider concider having a serpent or 2 to had to this list.
Remenber yet again i would wait for having the new dex before buying anything but that box and a spiritseer. I say that because this box is pretty cost effective, compare to buying them as stand alone, in worth case you can always sell on ebay what you are not using.
There you go hope it helped, wait for other opinion as i am not the most accurate of all the eldar poster in here
cheers