I've had mixed experiences but in general the risk is that your lecturer won't bend the rules as much as if they were just a tutor. That is, they're very strict on deadlines, assessment tasks, and not giving away much for the final... whereas student tutors tend to be a bit more relaxed and might be more accommodating. The plus side though is that whilst they have limited perspective, the lecturer usually knows what they're talking about and what the point of something was. e.g. if you prefix a question with "From the lecture" then they can answer it- whereas most student tutors won't be attending the weekly lectures and hence can't answer things like that.
It really does depend on both the subject matter and the individual though. I've had some lecturers as tutors who were more flexible and supportive. Some will even take feedback on board from tutorials and adjust the lecture content accordingly if it's clear that some concepts need more attention.