We have the requirement of deploying Office Web Apps on SharePoint Foundation 2013.
So, I am just curious to know whether there are any limitation, drawbacks etc in using Office Web Apps with SharePoint Foundation 2013
You need to deploy a separate server dedicated to Office Web Apps that does not have SharePoint installed on it.
In order to edit files in the browser, it requires a license that you can get through Volume Licensing. Getting the Office Web Apps installation now requires you to go through Volume Licensing, even though the product itself is free for read-only.
Office Web Apps 2013 cannot be installed on the same servers as SharePoint 2013. It needs to be on its own hardware (but can be virtualized). If you are going to build with high availability in mind then you'll need more than one server and a load balancer. In addition, if you are going to publish your SharePoint farm on the internet then you'll need to expose the Office Web App farm also.