I played Total Club Manager before they changed it into FIFA World Manager or whatever it's called. Since you're asking, I'll give you my main gripes.
1) I built youth camps in every country on the globe, at a cost of around £50m. I also upgraded my youth centres, hired the best youth coaches, and signed all the best prospects at every age. However, none of them were good enough for the Premiership. Realistic? Maybe. But when the Premiership's top stars were Raul, Ronaldo, Nistelrooy, Zidane, Figo in 2010/11, you start to realise that re-gens don't work.
2) There were two scores. Fitness and fatigue. Fitness decreased slowly season by season, while fatigue increases season by season. I invested around £10m each season on sending the team to specialist holiday camps where fatigue and fitness were meant to be improved, but it never worked. Eventually the players were flopping around all over the pitch due to a lack of energy. This got worse season by season, regardless of player age.
3) The tactics were ridiculous. There weren't any positions so to speak, positions moved like they do in FIFA or Pro Evo. Also, every player was scored out of 25, which meant that scouting and so on was worthless. Whoever had the highest score went in the team.
Having said that, it did use a FIFA engine for graphics so it looked lovely. It doesn't even compare to FM.