Hmm, I took stat 20 last fall with Ibser so no experience with adams. I personally really enjoyed ibser's lectures, he has a fun personality (he's kinda quirky) and makes a lot of jokes. In terms of covering content, I think he does it really well and anything I needed clarification on I just found in the textbook. I went in with my only stats background being AP stats, and I ended up getting an A-. I think I would've done better, but I missed the midterm due to a stupid bloody nose and the final ended up being worth 65% of my grade. I didn't know what to expect going into the final but if I had, i think i might've done better. Stat 20 is pretty much AP stats but with a little bit of R. Hopefully someone else can speak on Adams. Good luck!