The story here is pretty good despite a few flaws, namely:

1) Prakan's initial hostility towards Tua Phee is not very logical because (as he later seems to understand) Tua Phee does not cause anyone to die but merely sends souls of the dead on their way. A doctor getting angry with Tua Phee is like a doctor getting angry with someone who provides funeral services--the latter doesn't cause people to die.
2) For a large part of the series, it is not clear when Tua Phee's love for Prakan becomes romantic love. The changes in feelings could have been shown, especially given that when Pua Phee is alive, Prakan is only a kid.
3) Like many supernatural series, it is hard to have a truly happy ending (think: The Miracle of Teddy Bear and Something in My Room). Even a happy ending has to deal with some of the sadder things in life, but the audience may prefer their BL series to be more escapist. And it is even harder if you don't want the ending to be too predictable.
4) Too many deaths/near deaths of the main characters (sometimes for no good reason).

Still, Dear Doctor, I'm Coming for Soul has a rather good story that is competently told. Prakan's character is flawed, but he doesn't get to the point where he becomes annoying (at least for me). Apart from Prakan and Tua Phee's romance, another relationship that is nicely portrayed is the kinship/friendship between Prakan and Metha. Yacht is really good as Metha, conveying the characters jealousy while convincingly maintaining the fundamental righteousness of the character.

The side couple, Natee and Keeta, is cute--a nice addition to the story without being digressive or excessively sweet. At the same time, Metha and Nuch's love for each other is also portrayed in a way that will make us wish they end up together but doesn't get in the way of the more serious parts of the story.