MathWorks offers the Simulink product family including the Simscape physical modeling suite, simulation, validation, and testing tool set, a 3D animation module, signal processing toolbox for wireless communication, control systems, and event-based monitoring, to aid in the design of complex systems.
Simulink is a great tool for designing systems in the very early stages of projects. This lets you understand concepts and have a working model much faster, saving you time and money by being able to find errors really quick. On the other hand, when the projects reach a state of deployment you'll need to translate all the acquired knowledge and/or data from Simulink to the specific system you will be using. For example, you might design and validate a spacecraft propulsion system in Simulink, but when you build the real life model you will need to translate the designed algorithm/system to the actual code running aboard the spacecraft.
Learning curve for designing accurate models and getting useful results can be pretty steep for most people that aren't used to graphical based design and representation of systems.
Simulink requires a lot of CPU power and computer resources to run smoothly without crashing. Together with the MATLAB environment, a standard installation consumes a lot of disk space and becomes greater when more toolboxes are included.
Community for Simulink support and documentation is inferior to that of MATLAB and it isn't used as a standard tool by most of academia. I believe other tools such as Labview are far more common, making it easier to get help and find examples online.
Control blocks and more detailed algorithms can be run in Matlab Simulink. Simulation and PCB drawing of electronic circuit boards are performed in Proteus.