SQL Server vs SOLR (Or any document db)

I have my "customer" data in a normalized sql server database. Getting out the customer data in my app is taking too long. This is because I have to go to 10+ tables to get all the data I need. My company has an installation of SOLR that I thought about storing a Json object that contains all the data I need for a single "customer" already put together. I think that this would give me some significant speed improvements. However, it got me to wondering what the difference would be to me putting this data in a single table with a varchar(max) column that has the Json in it. I could index my 10ish searchable columns on the same table as the json. I know that document databases are very popular. **So I imagine there has to be benefits over just rolling my own using denormalized data in sql server. Can someone tell me what they are?**