Although I have never had any problems downloading/installing games from MyPlayCity other than the shortcuts being set to run in admin mode, there is a new development that you need to be aware of.
They don't hijack your home page, they don't force (or even try to force) toolbars on you and the games themselves have no ads within them. However, they do have ONE ad ONE time during loading.
The last few games I've downloaded from them has done the same thing (including the new one "The Last Conundrum of Da Vinci" that was just released today) - the first time you run the game (or until you successfully load the game itself), you get a small "this game is supported by" with a small ad. It's not long and after that first time, you just get the small white window for a few seconds and then it goes on to the normal game load.
I warn you because it's unexpected and the first ad I saw with Conundrum made my Avira Personal's Guard upset. It blocked it and the loading of the game load failed. I simply tried again, got a totally different ad and then the game completed the load.
Subsequent loads of the game have not had the ad and there are NO ads within the game. I'm willing to put up with a one-shot deal but if they start putting the ads inside the game, I'll stop using MPC!