The first game was a properly great piece of space opera in a fantastically imagined and created universe. Shame the game itself was a bit shit, like.
By the second game they’d moved on most of the original writing team and had been bought out by EA besides. The character writing was great and managed to involve you in a story which was properly terrible and completely broke what the first game had set out, on reflection. The game itself was servicable.
In the third game them not properly setting up an over-arching story came back to bite them on the arse and the writing is properly, properly awful, insultingly bad if you replay it. The game itself was actually good, good enough that the dreaded stapled-on multiplayer was really good.
Tl;dr Bioware’s game craftsmanship improved as the series went on, their writing furiously pedalled backwards.