The physical appearance should be the same as a new machine effectively.
The packaging will be more basic though. You probably won't get the fancy colored box that a new machine comes in, but a brown one.
The refurbs are normally solid machines with a full warranty, which can also be upgraded to Apple Care.
Here is my only caution. They don't discount the refurbs very much, in my opinion. You might be able to get a new machine from somewhere like Amazon or Mac Connection for almost the same price.
A new machine potentially helps resell value as it would have the original fancy packaging and whatnot.