Redstone doesn't work like it's supposed to. None of the BUD and most observers don't detect anything, tripwire hooks work only 1 out of 5 times, etc. I wouldn't recommend people who have big farms that depend on BUD to load the chunks until it's fixed or they'll have to go and manually update everything.
Redstone doesn't propagate properly through unloaded chunks, so if you run a signal more than about 10 chunks (160 blocks), you will run into this issue. If you are on a server, often times they will decrease the chunk load radius so it is less than 10 as well. I believe at one point Mojang/Jeb said they had fixed this, but they hadn't. However, they are hopefully working on it and it will be fixed in the near future.
Redstone is nerfed because survival got too much lag from redstone. You can only use slow clocks or anything that doesn't give a redstone signal too frequently.
