As to the pros and cons of two products, you need to know that vSphere Replication is a product which is likely to meet bunch of end users’ requirements. However, it happens even with the good product to have few limitations.
Here is a list of those that cross my mind:
• vSphere Replication in contrast to Veeam provides single restore point only. And it seems to be a limitation number 1.
• No traffic compression.
• No traffic throttling.
• No re-IP upon failover.
• Basic VSS quiescing (no application-aware processing, which is necessary for replicating VM running VSS-aware applications (such as Active Directory, Microsoft SQL, Microsoft Exchange, SharePoint), since this functionality guarantees backup transactional consistency of such VMs).
Probably, some of these issues are going to be addressed in the next releases by Vmware, will see.
Hope this helps.
Thanks.