I don't know what your price range is or what other sewing you do. I serger is a must for garment and home dec construction. I use mine daily when I am making Linus quilts. I make simple ones that are made envelope or pillowcase style. I use the serger for constructing the envelope. It finishes off the seam and cuts off the excess fabric. It also comes in handy to sew around the raw edges of the backing for a regular quilt, no ravels. There are quilt as you go methods that can be done with a serger. When I worked for a Bernina dealer I attended a class where we made a small quilt and a quilted and ruffled pillow completely on the serger and even installed a zipper. If you look at the construction of most of your store bought garments they are made almost entirely on a serger.
I recommend purchasing one with a built in rolled hem capacity. Except for the cheapet ones most of them are very easy to thread. I prefer Bernina's but that is my personal prefernce.