Advantages and Disadvantages of using tilemap?

Hi,
Lately I've been trying out the tilemap as i used to have a separate gameobject for every tile with a sprite render before i found out about it, and i wanted to try it out to see if its better in general to use it. Are there any advantages to using the built in tilemap rather then having a gameobject for every tile and also what are the disadvantages to using the tilemap?
The main reason why i'm curious about this is because i want to make a tile blending system so that my game looks more "professional" without hard lines between other tiles and more of a soft blend, is there a easy way to achieve this using the built in tilemap, or would it be better to use my own tile system?
Another concern is flexibility, as i'm new to trying out the tilemap i'm not sure how flexible it is and what it can do, if i decide i want to implement something which the tilemap can't do then i would have to take a lot of time converting it to a custom system.
Thanks.