This is a good recipe, it just needs some tweaking to make it great. The biggest improvement for me was adding a tablespoon of miso to the broth. If you do this you should also add two cups of water. This gives a better ratio of broth-to-solids and adds some great flavor from the miso. Also, I would use Soba noodes and add them at the end. You don't want to overcook the noodes!
Also, it should be noted that "hot pots" or "noodle bowls" are a one off recipe. You should only cook the amount you're going to eat. Noodles don't store well in liquid.
What I do is cook a large portion leaving out the noodles. This way I can quickly heat up one serving cooking the noodles as needed and avoiding soggy noodles.