You shouldn't have any problem, you'll need a new sim card for sure however.
You can get one at a kiosk or Mobile Shop or online.
Just a word here, IMHO the Samsung Galaxy Ace is a terrible phone and plagued with issues. You may want to look into getting a new phone when you sign up. Koodo has some models that you can even get with no cash down. There's even a nexus 4 you could grab free (if your credit qualifies you). I understand if you just want to use the Ace. But it's an old phone. Not even in the lineup anymore.
Phones to look at with no out of pocket costs:
Samsung Galaxy Discover (android)
Nokia Lumia 520 (windows phone)
Samsung Galaxy Ace IIX (android)
Nexus 4 (free on Tab Medium)
IPhone 4 (free on Tab Medium)