Arrowhead plant is one of my few long-term houseplant success stories. Yours looks basically OK, it's just young and new, adjusting to its location. There are actually several plants that were stuck together in the middle of the pot, shortly before it was sold.
It helps to understand that these plants are rain-forest vines. They stay small and cute for awhile, then will start to vine. In nature, they will eventually climb a sixty foot tree to the top. It will never be bushy, but to encourage a fuller plant, you have to cut off those vines when they start. You can easily root the cuttings back in the pot, this will give you that fuller look you'd like. The cut stubs will either branch or re-sprout from the root.
Mine does well with not much light. If the leaves get pale, it's getting too much light. The soil stays slightly moist, but sometimes I forget to water and it gets quite dry. I haven't repotted in years, but I sometimes add a tiny amount of fertilizer to the water. Growth tends to slow in cooler weather. I regularly have a few dead leaves, nothing to worry about.
I've given away lots of cuttings, it just takes awhile to get that growth going. Enjoy your plant!
