There is a great deal of evidence to support the use and demand of thin computing. It does show that significant savings can be made as well as achieving other advantages that cannot be monetised but that are of value to an organisation.
The main downside is that remote users will have access to their documents and applications only if they have internet access and there are no issues with the server or electricity supply. Should, for example, a user lose a broadband connection then they will not have access to any information.
While the chances of this are slim, you need to pay attention to your organisational and individual user requirements and so it may be a case that you allow some users PC access rather than installing a 100% thin computing system. Naturally, it can be argued that a remote user with a PC who has a hard disc failure or other technical issue will be in the same position, but this still needs to be considered.
Overall, the potential benefits will probably outweigh any disadvantages, but be very sure before you buy.