Take some facts from an actual blader and not some loudmouth with an avatar featuring snoop dogg having a seizure...
Bladers hit low, but hit more in 1 skill. It might not be the fastest, but it does basically the same damage as a glaive or bow when you add it up.
They can level fast if you know how to use them. Try to find things that you can kill with 1 soul cut + 1 chain. Get a blade with good stats and a nice shield, youll do fine.
They sure as hell look nice
Personally, I dont have a problem killing people in PVP, even before the euro update. At the lower levels youll have some trouble, but once you get some knock-downs and stabs youll be ok. At level 73, you get lightning chain which helps a lot... and if you plan on playing another 1-1.5 years, the 100cap will favor bladers more than anything.
Negative: You cant use your knock downs in parties or jobs if your other teamates dont have swords or blades... it makes it so they cant attack and its not very helpful.
Negative: You wont get very many unique kills.
Negative: Its a bit more expensive since you have to buy a weapon AND a shield.
Simply put, theyre a good build especially if you dont like to die. People saying they cant kill got no skill (oh yeah, bustin' rhymes like snoop dogg!)