Playing as a preferred status player (I had to buy some Coins because there are things in a game like this that I need like a hidden head slot) I know that it's still fun if you approach it as a single player game levelling through the storylines. Ive taken my time with it (2-3 hrs every 2 or 3 days) and really enjoyed the storylines and the progression of my character. It's really a lot of fun and it doesnt feel as grindy if you immerse yourself in the game.
Cartel Coins can be useful for getting little kick-knacks to help improve your play but I levelled my first character to 25 completely free before I needed to add some upgrades. It's also helpful that you can buy items from the Cartel Market on the Galactic Market. Helps fill in extra holes.
I say give it a try at least. It's free so you really dont have anything to lose.