Advantages: Does not have to be repaid, like debt does. Gives certainty of valuation for your company which can also be a disadvantage if the value is too low (for diluting founders’ stake) or too high (which can impact interest from next round investors who do not like to price downrounds from the round before, to avoid legal risks from diluted shareholders).
Disadvantages: The most complex to structure (highest legal bills, longest time to close). Usually involves giving some level of board control to investors.