If your first camera is a Sony FD-90/85/73, then I would encourage you to purchase this starter kit for both conveinence and peace of mind.To begin, the battery itself is what makes it worth purchasing. Most batteries will rack up quite a bill so it's usually to your advantage to buy in starter kits. Not to mention I would strongly recomend against buying third party batteries like polaroid etc. Such batteries void warranty on the camera itself and are not up to the same level of quality as Sony batteries are.
The case is also the best size for the Mavica series, the problem with other brands and sizes of camera bags is that the Mavica is a monster of a camera, it's huge and an irregular size, making it hard to find an ideal case.
The disks, the lens cleaner are really not as important as the battery and case itself, but certainly save you some trouble from having to buy disks and a cleaner.
If you're an amatuer or professional photographer, it is still to your advantage to purchase this kit, however, you might wanna consider investing in a larger case since many professionals and amatuers carry more accessories then you're regular Joe Photographer and the Mavica case is designed for the camera and the kit contents only.
