His lectures doesn't help. Study by yourself. I haven't attended most of the lectures and even traveled to Hong Kong before final while still got an A.

Personally, I feel like Prof Gieseker is a really nice teacher and genuinely cares if the students understand the course materials. During office hours, he will always ask student what their career options are and make recommendations on courses to take based on that. The downside is that sometimes we fail to get enough constructive work done during office hours. (That's why the class relied almost entirely on our TA for homework and clarification of concepts.)

I must say that Prof Gieseker is getting old and frequently make notation errors. These errors do make the class hard to follow initially, but you will get used to it in a few weeks. So I found his teaching generally acceptable. However, he's kinda slow in doing questions, or understanding questions for that matter. So if you had anything theoretical or conceptual that you wish to clarify, I would suggest looking for your TA.

Grading wise he is pretty lenient. He doesn't hesitate to give you A if he feels that you understand the course material. For midterms and final, he will provide at least 3 years worth of past midterm/final questions, and the format of most is largely the same. If you do them all you should be fine.

Conclusion:
Yes, he is a pretty decent professor. Humorous, gives decent grades, and approachable. Just get used to his teaching and be more understanding in him making mistakes, instead of fretting and complaining.

he shoudl not be teaching anymore, as in he should be retiring, great guy, very nice has a slight sense of humor about math but id definetly bnot recommend him for and lower div. i took him for honors linear algebra, his lectures are very boring which makes it hard to listen to, all this aside he is an okay grader.

This guy is an awesome guy, very approachable, helpful and easy to ask for help. But the fact still is that he is incredibly slow paced, to the point of irritating. As much as I love the material, I can't stand the fact that he goes so slow; I mean he covered two chapters in 4 weeks, which is a ridiculous amoeba-paced slowness that is mind numbing. Maybe it's because there's a trio of clowns in my class who constantly ask irrelevant questions and slow everything but some people do try to learn and it's frustrating. He should set a course plan and stick to it instead of wandering off and explaining other concepts, interesting as they may be; it's up to the student to investigate and learn extra material, not the professor's job to spoonfeed everything.