ASLA offers great support for both physical model development, as well how to develop applications that run simulations in parallel with it's MPI libraries.
It also has many tutorials online which make learning very easy when compared to other simulators like OpenFoam or Anasimba/XFOAM. I would say there isn't much we dislike about this simulator but maybe more features could be added such as user defined materials etc., however if you are looking at solving CFD problems then definitely use AslA! We have been using its capabilities of developing models quickly without having any prior knowledge of physics involved within them.