79S, Bear in mind that all certified airplanes are certified to a standard of "must not require unusual pilot skill and attention" [to fly]. Yes, different types, obviously have differences - that is the point. But, within a class, those differences generally won't be so great that a reasonably practiced pilot can't manage okay. Certainly a Cessna 150 to a 172S is completely within the realm of "you can manage". I extend this statement to transition between C172/PA-28 fixed gear series.
That should not be taken to mean that you don't bother to understand the aircraft, nor seek some training. But, you should feel confident in going ahead with the flying. The fuel injection requires a little more awareness, and slightly different technique - so read the flight manual.
Where you should be much more cautious, are future class changes. Transitioning from C 150/152/172 to a C 177 or 210, for example requires some training, and mentored practice. A part of this is of course retractable gear, which should be trained to you. Flying the T tailed PA-28's requires type specific mentoring. And, of course, tailwheel and float flying require specific additional training.
One of the skills you want to build in piloting is to be confident in learning a new type. Certainly, ask type specific questions here, but read and understand the flight manual for the aircraft you propose to fly. Don't fixate on memorizing speeds to the knot, the ones you must know are marked on the airspeed indicator - by regulation. Rather focus on understanding the systems and differences of the aircraft, and how you will handle an unusual event without fumbling for checklists. Use the checklist to check that you're already doing what you should do, rather than as a recipe for flying the aircraft.