In my experience, they're worth it if you have more sensitive skin, like I do. If I shave with a cheaper dual-blade (even a nice Gillette one), I get really bad razorburn. Depends on your needs, I guess.
Try the old school saftey razor type. Much finer control on the angle of the blade, and overall a much closer and comfortable shave. Haven't looked back on the cartridge stuff since, 10/10 would recommend
Oh yeah, I have no personal experience on this, but shaving soap/gel is said to be easier on the skin. The propellants in the spray stuff dry your skin out