It will not look any different, except if you decide to use the Client 2008 (recommended). Both clients can co-exist on one machine, so that is no big issue.
SP27 will give you some added functionality, like e-mailing in Service calls. Some functionality is changed. Read the releasenotes to see if the other changes will affect you. You don't give any details about your system or setup so it is difficult for me to say.