Yes it did. They changed a lot of stuff to make it faster and "more accessible". It completely threw off the balance. Stage 2 on PC did get some new characters, but they're just variations on the characters that were already in there, and some maps were tweaked, often for the worse. They also massively downgraded the graphics, for some reason. I guess so it would run on as many machines as possible.
And no, sorry, it wasn't terrible on PC. If you're not into the type of game it was, that's fine, because they were very bad at communicating that it was essentially a FPS MOBA and it seems like that rubbed a lot of people the wrong way. But it was a well-made game that suffered from (IMO) hysterical overreaction to DLC and a disproportionate amount of "esports" hype.
well I am on the other camp. I got my Founder's reward, played extensively pre and post F2P.
Pre-F2P, I found the community to be toxic/elitist. They would curse at you and trashed you down for being new. It took very long time to set up a match. The game remained botched and broken with poor netcode and matchmaking. Monsters were imbalanced. Ppl who cheesed were the vocal one who scream "bloody murder" when their broken game got upgraded.
Post-F2P, the AI bot seems improved to take over missing/AFK player, maps are better balanced with less cheese, monsters got rebalanced with bug fixes, new monsters added with new twist, new character added with new ability and the community was quite fun to play with. Co-op mode got added and what a fun ride that was. Yes, I take the post-F2P version any day. Hell, even the tutorial section got re-done and was more accessible for new players. I believe that they still keep the old version pre-F2P up somewhere (maybe in beta branch) but can't confirm this since I didn't want to go back to pre-F2P version.
For what it worth, the post-F2P version was 2 step FORWARD and maybe 1 step backward for the cheesers. I don't miss them. I don't miss the toxic and elitist community which was plagued with hacking pre-F2P.