Yeah Shin Megami Tensei is often abbreviated as SMT. I'd say with P5 if you don't like it by the end of the first palace, then you probably won't like the rest of it. You've seen most of the core gameplay and mechanics by then. I would definitely say play P5R and not vanilla P5 if you have the option. Some mechanics are changed in P5R that make it a smoother experience. The big new additions are mostly at the end, the "Third Semester".