I personally think they are great. I was doing an engineering school but I decided to switch to a theoretical physics master for my last year: I wouldn't be doing a PhD now if I didn't have the chance to find these courses on the net by Prof.Susskind.
They cover a lot of material and give you a (strong) theoretical minimum. Of course I had to go a bit deeper during the physics master into some specific materials (statiscal physics or QFT for example), but the basis he gives in classical mechanics (hamiltonian formalism, lagrangian etc) which I never studied before were sufficient to understand the rest. Not to talk about the very good insights he gives to any material, ones you won't find in any textbook..