Use it wherever you like, just realise that it will sound off on every bit of junk in the ground and will be a bit noisy in high iron mineralisation and hot rock area. (It is set up for salt beach work).
Generally speaking, PIs tend to be a bit of a handfull in parks and gardens and tot lots and wherever there is a lot of electrical interference, but on the other hand you will find a lot of stuff. Personally I do not use a PI for general on land coin and relic detecting and prefere a No Motion VLF discriminator detector that has manual or auto Ground balance, good discrimination ability and a sensitivity control.
The silent search motion vlf discriminators are also very good but tend to get slightly less depth than the Ground Balancing types.