When 5th edition hit, Norau and I were relatively unaffected by the dreaded true LOS (Line Of Sight) rules. We had always used terrain pieces that were high enough to block LOS to most things. Granted, C'Tan and Land Raiders were hard to hide, but we didn't see this as a problem.
My buddy Briefspite, however, actually dumped 40k for a period of time because of "true LOL", as he calls it. I see his arguments, but my counterpoint was always that the terrain should be used to provide not only cover, but block LOS completely. In my opinion, no 40k board has enough LOS-blocking terrrain if a unit can have complete view of the battlefield.
Norau and I were using fairly large hills to achieve this. Briefspite has a lot of city terrain, that he wants to use for tournaments (after grudgingly admitting that 40k is fun after all, even with true LOS). To achieve "5th edition compliant" ruins, LOS had to be blocked. Not only for the little guys, but also for Carnifexes, Land Raiders and Defilers.
Today, we painted up the first building to a good gaming standard. This building blocks LOS in almost every direction. If you hold this building, you can get good firing positions if you want, or hide safely inside if that's your cup of tea.
Note that all the pieces for the ground floor are completely blocking LOS. We think that this will force players to use this tactically. Gunline armies are all great fun for about five minutes, but it takes the small gribblies, the guardsmen, the Fire Warriors and similar infantry-sized models to really shine here, in an environment where tanks cannot move, and Lascannons cannot get LOS to the target.
Our first building painted up.
How much terrain do you guys normally play with? Have you changed the way you use terrain after 5th edition was released, or have you just changed your armies?