I should note that even if Installer 4.0 is released soon, it will not magically have all the apps it used to have for the 1.1.x phone. Due to the changes in 2.0, all apps will need to be ported over, and some probably won't make it. At the moment, apps are being slowly added to Cydia at the rate of ~2-3/day. Many of these are still low-level unix/developer stuff that isn't of wide interest, but there are some games etc too. When Installer comes out, I expect apps will probably be listed in both apps and they will have similar selections.
Cydia and installer do virtually the same thing. Installer is "prettier", and has apparently upgraded its back-end package system (which was much less stable and less efficient than Cydia previously). Until it is released, we won't know if it is better or not overall.
I don't understand why some people are so anti-Cydia, I think because people compare the old Installer's range of apps to the current 2.0 Cydia and think it sucks in comparison. As I mentioned, the current lack of apps is due to 2.0, not Cydia!