I'v followed circuit simulators for 15 years,,, Multisim, Proteus, Orcad, Tina, Pspice AD, etc.. Multisim was one of the first simulators running spice simulation and advertising in electronic magazine's like "Popular Electronics".... It's a good Starter but is more for students and has very limited microprocessor support . Proteus is more professional engineering design software and is now my overall choice for analog and digital mixed design. There is always "speciality" type simulators for rf and microwave design etc, but Proteus gives best overall technology design help. I do find that upgrades or real advances to the simulators takes years and does not seem to be a priority to the companies leaving us with " This is the best your gona get for the next xxx years"... Ahhhhhhh