Editing Warhammer 40,000/7th Edition Tactics/Chaos Space Marines (section)

===Cons===
The current Chaos Space Marine codex book is the oldest in current use, and it shows. The fluff and art are top tier, but the rules in it are clearly written for another age - one without grav and knights all over the place. Make no mistake - you'll be fighting an uphill battle all the way in every game if you try to run a CSM army as just a CAD with just the rules in that book - and that's just in CASUAL games. There is a good reason why an Ork, Tyranid, and CSM players arguing who has the worst codex is a popular online cliche. Luckily, as of the end of 2016, CSMs have finally gotten a boost in the form of powerful and varied (if spammy and often overcosted and/or tactically infexible) formations that can be found in the Traitor Legions supplement.

Most of the issues have generally come from Chaos being compared to loyalist Space Marines (and their many variants). Among them are:
*'''They Shall Know Fear:''' Unlike vanilla Space Marines, you don't get "And They Shall Know No Fear." Considering the advantages of ATSKNF are four-fold (Auto-pass Fear checks, immune to being destroyed by sweeping advance, auto-regroup regardless of how many models you have left, and suffer no move/shoot penalties after regrouping), the regular Chaos Marines are in an unenviable position point-for-point. However, it's not all doom and gloom: Unlike the loyalists, you get a fair few options for making your guys Fearless or superior Leadership so you're less likely to fail Morale checks in the first place. Inversely, if you're running MSU units, you don't care too much about trying to rally "that one last" model for any given unit when you can have two more small units in backup. 
**'''Note:''' If you're running a cult legion from the Traitor Legions supplement, Veterans of the Long War is fearless across the board. Thus this one issue can be discounted, if you wish to theme your army based on a named legion rather than Crimson Slaughter or your homebrewed warband.
*'''Beggars of the Long War:''' As a price for Chaos getting access to more consistently powerful Psykers, herohammer blessings, and general "unconventional" power options, they're missing a lot of powerful tools the Loyalists get access to. Most notably, your army lacks Grav Weapons which are considered "the one special weapon to rule them all" for normal Space Marines. You can find "analogues" for some of the other tools Marines get that you don't, though you also lack good equivalents for Drop Pods, Razorbacks, Attack Bikes, or flying transports. Forgeworld can potentially mitigate this to some degree if you wish. You'll see other small examples of Chaos technology being more "dated" or second-hand than their Loyalist counterparts, discussed in their individual unit entries.
*'''Tactically Inflexible:''' Chaos Space Marines have no units with the innate ability to Infiltrate or Scout. They don't have any special rules or wargear to get better deployment options, to have better chances of selecting a table edge or to Seize the Initiative, to improve their Reserves rolls or to mitigate scattering from Deep Strike (the Dimensional Key doesn't particularly count). Unlike many armies, they don't get many non-psychic "toolbox" abilities; there is no Combat Tactics/Doctrina/Canticles equivalent, nor do you get stuff like Guard Orders/Acts of Faith. 
*'''One Codex In (At Least) Two Books:''' The CSM codex is OLD AS FUCK. The rules in it are dated, and power creep means that it hasn't aged well. To GW's credit, as of the end of 2016, steps have been taken to bring CSMs up to speed. That's all well and good, but unfortunately the 'update' was done through the issuance of supplements rather than an updated dex. This means that you have to own the dex + one or more of the supplements in order to build a passable army, and if you want a really decent one that supplement has to be the Traitor Legions or The Traitor's Hate. Woe betide anyone wishing to actually collect all the books in order to have access to all the current rules - there are, like, 6 of them, before you even dip your toe into Frogeworld and Apocalypse.