The nice thing about compressed loads is that it's impossible to double charge a case. As far as whether they're more accurate, I would say that it depends. A quite accurate load I've made up for my 222 Rem. consists of a compressed load of Winchester 760 and Speer 60 grain bullets. With the twist in my 222 barrel, it shouldn't be able to stabilize 60 grain bullets so there must be something good about the load.
In the above case, the 222 Remington is a fairly low pressure cartridge of small diameter so even if overcharged, it shouldn't overly stress a strong gun. I wouldn't be above trying compressed loads in higher pressure cartridges but would exercise a lot of caution. I also don't compress the powder until it's realled mashed; just mild compression.
A bad thing about compressed loads is that you can't just shake a case to make sure it got a charge of powder.