Considering that I worked in one of the investment bank, perhaps I can answer some of your enquiry here. However, this answer is more suited for IB side & it will different alot if you are coming from corporate/SME side.

1. Working hours : 6a.m to 8p.m for 5 days a week. Sometimes, I have work to on weekends as well.
2. Working environment : I had alot of great colleagues but there were some bad apples. Nonetheless, I learned alot of knowledge that I use until now.
3. Training opportunities : I was sent to alot of trainings. Most of the banks training centres are located in Bangi. They have Public, Maybank, RHB & CIMB training center there.
4. Promotion/transfer : This depends on your boss & your performance. Speaking from my experience, I never saw anyone got promoted internally. All of my colleagues left to other IB for better opportunities & pay. This happens quite often & you will realize this as you enter this industry.
5. Staff benefits : This is where I believe no other sector can compete with banks. I was given 24 days annual leave, 18% EPF by employer, unlimited outpatient for me & my family. Even my friends my friends in Petronas was envious of me for this lol.
6. Hierarchy:  There is general misunderstanding when it comes titles in banking sector. Often times the title sound very bombastic but the pay is very low. Usually anyone with 3 years of experience can get AVP title in the bank that I worked previously. I even know someone with a title " head" but his pay was just 7k. So don't fully rely on title when it comes to banking. The grade is more reliable to judge your hierarchy than the title.

Btw, if you don't mind me asking, Which area of banking are you being offered ?