1. Some managers do micromanage you and irritate you which might be demotivating
2. Very few onsite opportunities (it may seem that the opportunities are more, but sometime politics play an imp role. Again depends on project)
3. Learning stops at a point of time where u should start considering other opportunities
4. Few managers are soooooo stupid that they neither understand technology nor management. In this case either move to another project or escape. Never try to make that manager understand something