Yup, the parasuco store on St-Catherine street is huge and was newly renovated for a year or so!
There are many stores on St-Catherine street, and as xoxo.juicy mentioned, the downtown shopping area connects five shopping malls together from Promenades Cathedrale to Complexe Les Ailes (stores like Lacoste, m0851, Swarovski) to Center Eaton (stores like Blue Marine, Pink as mentioned and toxic which locates beneath Blue Marine) to Place Montreal Trust (La Maison Simons and Style Exchange, and Inglot as mentioned) and to Les Cours Mont-Royal (which has many high fashion stores like DKNY, Three Monkeys).

If you have time, you can also head to St-Denis street, there are many great boutiques and restaurants.