Biscuit joiners make fast work of a number of joinery tasks, but are they a tool for "serious" woodworkers? It depends on the task and your priorities. It is virtually impossible beat biscuit joinery for speed. In his comprehensive guide "Success with Biscuit Joiners," Anthony Bailey leaves no question about the versatility of the method. On the other hand, there are times when more traditional joinery methods are preferable, as Michael Dresdner and Woodworker's Journal editor Rob Johnstone point out in their answer to a Woodworker's Journal eZine reader's question:
Q. I am building a red oak curio cabinet, and I was wondering if biscuit joints would be as good as mortise and tenon joints. I don't have a mortising tool, and I haven't had any luck with handmade mortise joints.
A. Michael Dresdner: "As good as mortise and tenon? No. But that does not mean they will not be adequate. Properly done, biscuits can be very strong and very appropriate for woodworking. However, I would stop short of calling them equal to a properly executed mortise and tenon. Still, I think the objective is to make it good enough. As Hallack Brendan once said, 'Sometimes, the best becomes the enemy of the good.'"
A. Rob Johnstone: "While I must confess to having just purchased an new biscuit joiner, I am not a huge fan of the tool for tasks like constructing a face frame. (I am sure that they are sufficient to the task …it's just not my method of choice.) I like biscuits for helping to align glue joints; that's where they really shine."
From the Woodworker's Journal eZine 2004 archives
As Rob mentions, biscuits are extremely handy for reinforcing and aligning edge-glued joints. And while he's not a huge fan, many woodworkers swear by the extra-narrow face frame sized biscuits, available for use with the Porter Cable Biscuit Joiner, as a frame joinery method - especially in situations that make pocket joinery impractical.