This article is my second on the topic of the new dark eldar. It is meant as an introduction to assess the army as a whole, comparing their strengths and weaknesses versus the current top tiered lists. I consider Blood Angels, Imperial Guard and Space Wolves to be the three strongest armies. Blood Angels can be competitive as either a mechanized army (razorspam) or as a DoA army (jump heavy). Imperial Guard is most competitive as a mechanized army while Space Wolves have the largest number of varied approaches.
My introductory post on the topic of dark eldar focused on their lance weapons versus mech with the conclusion that lances in general are not good at wrecking/destroying armor but they are good at shaking and stunning vehicles. This observation leads me to believe that versus a heavily mechanized army it will require a multi tiered approach to beating them. For example you shake and stun a mech army with your lances and then assault the vehicles with haywire grenades. Haywire grenades are not the answer to wrecking or destroying vehicles as they only penetrate on a roll of six following the roll to hit. So as an example consider a squad of 10 Wyches assaulting a vehicle that moved up to 6 inches - 5 hit of which the majority will glance so again you are mostly shaking and stunning vehicles. Dark eldar will need an answer to removing enemy vehicles to be a potent force.
Remember that the majority of mech armies excel at shooting but are not strong in assault since their transports are filled with small squads (i.e., MSU or many small units). The exception to this are Space Wolves as they can run an MSU army and still field enough potent assault units. Blood Angels razorspam lists on the other hand are not a strong contender in close combat as their special rules tend to favor highly specialized units such as Vanguard veterans.