I made an attempt to learn to play Warhammer 40k in the past, and even have Deathwing and Chaos Space Marine armies. After spending 2-3 months collecting, assembling and painting my Frozen Fists, I got them to the local club and just couldn't get over the steep learning curve of the game. The rulebook is quite intricate compared to other systems I've played, and learning my own army, as well as that of my opponent, was too daunting.
So I put the 40k armies on the shelf and pursued other wargames. I found that, while those other wargames are awesome, it doesn't matter how great a game is if no one else plays it. So I'm now going to bite the bullet, climb that learning curve, and learn how to play 40k!