why? you may not have tried rock or just have had a problem with it before, but it is much better than cydia, why? Backups, i jailbroke on 4.0 using the tricky ibooty method and as soon as i opened rock i backed up to all the things i had installed before! it is much faster than cydia, no reloading data all the time, you can install many apps, and restart/respring after and it is much faster at fetching packages, when i first jailbroke ages ago, rock had many problems for me, crashing, not working but they have been fixed in updates. the only fault with it (or really with repo's) is that some dont work on rock, so sometimes i have to go back to cydia. this is my opinion and you are entitled to yours, post which one you think is best and why.