Well you won't bust any speed records, but the boat should get into the 30's without any real problem. A 150 is a good workhorse size motor that will basically get the job done without any flash. It's probably the best value motor option available, because 150-175hp is the last step up the power rung before things start getting REALLY pricy.
Overall, you should be pretty happy with it; and you'll enjoy the extra deck space the 25 footer will give you.