Pros
* open source
* it's own formats are supported by distributors
* active development (for now)
Cons
* no database backed schematic and layout
* cannot simultaneously view and edit schematics and layouts with others
* no integrated version control concept, Git is ill suited for ECAD projects
* no 3D viewer for schematics and layouts
* limited number of PCB layers
* mangles SPICE netlists
* no PSPICE support
* no IBIS simulator
* no EM simulator
* no Verilog-AMS simulator
* no Verilog support
* no export or import to common commercial formats, like OrCAD or Altium
* no features to avoid creating duplicate projects for testing subsystems
* no constraint checker for any design information
* no automatic SPICE/S-Parameter/IBIS model generation
* ngspice results viewer is very rudimentary
* despite review process, regulators and other parts that come with the preinstalled catalog are sometimes backwards from their SPICE models
* claims of an automatic footprint associator are misleading: it will only automatically associate by the "value" field of parts (i.e. no power rating or tolerance, other arbitrary info support)
* automatically generated symbols for KiCAD projects are often ugly and misleading: it would be much better for everyone if a 300-pin FPGA just looked like its footprint on the schematic; instead we get six or ten separate 60 or 70 pin rectangular squares with pins that are usually only numbered, not named
* automatic symbol generation from datasheets is nonexistent
* automatic part information pulling from datasheets is nonexistent
* no checking to make sure that parts from distributors actually have all their information filled out that was available, permitting lazy generators that don't embed the freely available models that may be available for the part
* no central, internet backed database that is integrated into the software for getting modules, parts, sheets, etc
* the module API is mostly useless