I've had similar ones a while back with no display, and it's amazing what they can offer today for the price. Don't expect super low distortion, and don't expect to be able to fix it if it breaks, but perfectly adequate for many tasks. A good troubleshooter might go for a used Wavetek instead. Much higher performance, but more prone to problems due to the age.
I am presently using the calibrator from my scope as a square wave source (I know, I'm just asking for it ).
I have tried a couple of PC software generators, but the output from these is unusible - top and bottom of the squarewave is badly rippled, sinewave looks "thick" on the scope.
You can "trick out" the performance of one of those inexpensive function generators with a pair of switched capacitor filters from Maxim or Linear Technology -- while I will credit the idea to Charles Hansen who wrote it up in Audio Amateur I had been using the same technique with a Basic Stamp. (This is not the Ayre Hansen, btw...)
If you get the TAA article note that you should recheck the pinout of the devices as there was a mistake in the article's schematic.