If weight is set up correctly, the biggest factor that makes strava power inaccurate is wind. On climbs it can be better provided it has accurate data for the incline. The power peaks are not accurate at all, which is what you refer to when you say 600W or 700W., I assume?

If you should get one? What are your goals, what do you intend to do with it?
The data it provides is fun in itself. But the way a power meter makes you faster is by allowing you to follow a structured training program, measuring your fitness level and then ride hard on hard days and ride slow on slow days. You can use heart rate for that, but that does not work for measuring intensity of short intervals.