It's easy to use - it is intuitive! You can do most of your work in excel or google docs without having any knowledge about yield modeling at all. The interface could be more user friendly but I think that this will improve over time as they add features like portfolio analysis etc. They are working hard everyday improving their product which makes me feel confident using them every day even though i'm not an expert myself yet :) Their support team answers quickly with helpful tips when you need help solving problems related to yields modelling. We started doing some basic calculations regarding different types of risks such us credit/equity spread costs during bond maturities so far no major issues encountered although there might still exist minor ones if one does not know what he / she is looking into.