There are definitely a few problems with the transfer system.
Player exchanges suck, I accept that they aren't common in England but I've never seen one happen at all in FM.
AI clubs never negotiate on a price when trying to buy a player, yet they do when selling. (Not a huge problem, you can just use offer to clubs)
Random instances where clubs are demanding more than the players asking price.
Generic transfers that happen every game.
AI managers are retarded and buy players based on rep regardless of performance and whether they even need said player!
Serie A has huge transfer flaws, player exchanges are common as are co-ownerships, both nearly impossible to get done.
All the above are just little things that annoy me but the biggest problem is when trying to sign a player.. If I try to sign a player who is on £50,000 per week he will not accept less than £49,500 and that's at a huge push!.. Yet he will sign for an AI club on £35k per week. Same for free transfers, a player asking for £50k per week won't accept less than £45k but he will join a club for £20k p/w, how is that possible? ): -