I had a couple of battles the other day; a 1500pt game and because we had plenty of time left, a 1000pt game.
First off was Chaos vs Chaos, I used Daemons of Khorne with CSM allies (2x Bloodthirsters, 2x 10 Bloodletters, Chaos Terminator Lord w. 5x Terminators w. assorted wargear, 10x CSMs w. Power Fist and Heavy Bolter in a Rhino, Defiler w. Power Scourge) whilst my opponent opted for Thousand Sons (Terminator Sorcerer w. 5x Terminators in a Land Raider, 2x 10 Thousand Sons in a Rhino, Spawn, 5x Havocs w. Lascannons).
His opening salvo destroyed my defiler, I moved everything forwards to try and engage him in close combat asap. My CSMs were severely damaged by a turn of TSon shooting but then a Bloodletter squad arrived and tied those TSons in combat for a while. One of my Bloodthirsters cracked open the Land Raider but was brought down by sustained lascannon fire whilst the other accepted a challenge from a TSon Aspiring sorcerer and after rolling terribly on his attacks he learned just how nasty force weapons can be and was insta-killed. My Terminators struck in and engaged his, mine dealing most of the damage but in the duel between his Sorcerer and my Lord I once more learned how nasty Force Weapons can be. So I lost this one.
Game two was much more one-sided. He'd come up with a 1000pt Eldar list but having seen what I was proxying, he altered it a bit to become (Illic Nightspear, 2x 10 Alaitoc Paathfinders (the upgraded Rangers that Illic can get), Wraithlord w. no additional weapons, Wraithknight w. no additional weapons).
I brought Imperial Guard with some help (Company Command Squad w. 1x bolter, camo cloaks and a Master of Ordnance, 2x Veterans w. camo cloaks, 1x bolter, 1x sniper rifle, 1x autocannon, Knight Paladin, Knight Errant).
His Alaitoc Pathfinders started in reserve and I took the first turn. The clash of the titans began as my big things closed with his big things, I also found that in the ruin-heavy map we'd laid out, the ignore cover order truly comes into its own. Illic manages to target my commander but a Look Out Sir! saves his life and an ignores cover autocannon saw the end of old Nightspear. The Wraithknight managed to inflict a couple of hit on my Paladin before engaging in melee, my Paladin went down to 1HP before annihilating the xenos filth. The Errant had no such trouble dealing with the Wraithlord at range. His Pathfinder teams appeared on opposite board edges and began exchanging fire with my veteran teams, all sides heavily entrenched at this point. One of his snipers took out a veteran and my men hit back stronger, throughout the game the Master of Ordnance did very little but with his big things dead, my Knights turned on the puny eldar and after a bit more fire they all fled the board. At the end of the game I had lost one veteran from my command squad and one veteran from elsewhere.
So the two things we can take away from all this; Force Weapons are really powerful, Imperial Knights are really powerful.