I agree that it's not the most useful tree/fruit, however:
- it's prolific, lots of fruit year round even on a small tree
- it looks beautiful, much nicer shape than a lemon, at least in my experience
- it's a fruit you don't find for pennies at the supermarket
- it has a distinctive taste that you can't substitute with lemon or lime, e.g. in ice cream or a tart
So our tree is definitely here to stay, but I would definitely get a lime and lemon first...