Currently our client is using Crystal reports (11.x), integrated with the old .Net desktop application.
Looking to move towards better reporting solutions: Dashboards, reports with filters, drill downs, better export options & formatting with excel. Still print reports, needs better printing experience with reports
Does Power BI can replace SSRS with reports + Dashboards or still need both to complement each other?
If your client absolutely requires printable paginated reports, you'll likely still want to complement Power BI with SSRS. I've also seen this as a pain point for some organizations, but in many cases I am able to work with a client to adopt Power BI as an alternative; one can make the case that paginated reports are not required when you have the ability to drill down and even export row-level data if desired.
In situations where all employees who need to consume the information have access to licensing and technology (even a tablet or phone will do), then you can potentially supplant SSRS/Crystal entirely with Power BI. Your biggest issues are going to be when reports are mass-printed to low-level employees in operational positions, particularly those who don't work on a computer.
This is definitely more of an expectations management conversation and working with the organization to distill down precisely what their requirements are. It can get political, and even if they don't really need paginated, printed reports, some users will insist on them.