No its not at all..so many armies do that. He wants it too be fairly competitive and eldar infantry is very flimsy. Its not 'lame' at all.
Basically, the harlequins need a shadowseer. There is too much non-scoring is the biggest problem though. 2 wave serpent/fire dragon squads sounds tasty but you are looking at 500pts of non scoring because of it, not a good plan in my book.
I personally think wraithsight is going to inevitably be an irritating factor for you as well but you dont want to go down the 3 holo-tank route so I won't advise it.
The main problems are you dont seem to have any decent anti-infantry. One of he fire dragon/wave serpent squads has to go to give your army such sort of punch against infantry.