Sceadwian said:
All you're paying for is the snazzy visualizations. Ltspice is nice and it's free, it does however require the user to tell it how it needs to view the various outputs and a user that knows how to interpret them to the same extent.
Proteus goes just a little further than that,
Ltspice's libraries are small in comparison, and it lacks in simulation tools (both analogue and digital) to monitor circuit behavior. There’s no PCB designing software with it
Proteus also allows people to insert their PIC/AVR/programmable device into the circuit, and execute their program with great accuracy, and step into the program - watching how the programs registers are functioning and I/O's function line by line if required.
For example, you can create a program to interface with an GLCD for your PIC, throw in a Graphical LCD in Proteus, wire it up, and watch your PIC program work by hitting 'play'. Easy as pie
As for PCB designing tools, when your done simulating, you can hit a button (Ares shortcut), and have you components auto layed out, slide/move a few things around, and then auto route with extreme efficiency to 1/2/3/4 layer pcb requirements. Then just print and Iron.