D-Wave doesn't have typical quantum logic gates. They are a different kind of quantum computer called "adiabatic quantum computers". Instead it solves optimization problems by using a technique called "quantum annealing". In essence, it's a tool that can very quickly find maxima and minima of certain cost functions you can program in (albeit tediously).
This is slightly inaccurate. Adiabatic quantum computing is not the term you want. Adiabatic quantum computing is equivalent to the more traditional quantum-gates based computing model (both of them are efficient at the same class of problems). D-Wave can solve one particular problem (that can also be solved by classical computers in similar time), the problem is related to annealing, and is not the problem of adiabatic quantum computing (which is much more general).
The component they lack is that they can not preserve any non-trivial information between their qubits.
