Over the years I've seen several posts on people considering jobs at Big4 corporate finance / M&A / TS departments, or people making statements about these jobs which have some pretty large inaccuracies. I'm going to try and clear up any confusion over the topics here....
Big 4 corporate finance
The corporate finance departments at Big4 essentially offer MM boutique bank advisory services. You will do sector research, deal sourcing. deal advisory, act as sponsor / Nomad (in the UK). You'll do a lot of work with PE firms, especially if you're in a capital markets role.
Many of the people here have superb backgrounds and join from bulge bracket IBD teams or elite boutiques. For example, some CVs of people I work with include head of IBD at BNP Paribas, MD in ECM from JPM, head of corporate broking at a mid-cap bank, ED from CS etc.
Usually you will be separated into sector or product specific groups (i.e. TMT, Industrials, IPO). There is slightly more focus on private company work rather than public, i.e. small / mid caps. It's extremely unlikely you'll ever be working on a mega cap deal that makes the front page of the FT/WSJ. Typical deal sizes are usually $100m-$1000m. Deal volume is pretty good depending on sector conditions.
Workload is lighter than at a BB, usually a more friendly and relaxed culture, work with top tier people, exactly the same work as in IBD, work very closely with company management and PE owners (if applicable).
Have to work harder to win deals, less 'prestige', usually lower bonus potential (base not too different), no real access to institutional investors if you focus on capital markets, less valuations and technical modelling work than at a BB, but still good exposure.
Big Four Transaction Services
TS in particular is an area where there is a lot of confusion. It's often referred to as M&A deal services or something similar.
You will be working entirely on M&A deals, usually with PE firms. The work you do is financial due diligence, i.e. digging into the company to find any problems with it, verifying whether forecasts are reasonable, whether the company is likely to run into difficulties, producing summaries of business performance over the last 3 years etc.
Again, you'll be in sector or product groups. Deal sizes can get very big as Big4 are pretty much the ideal companies to hire to undertake DD on mega cap deals.
Lots of deal exposure, learn a lot about the companies you're working on, do a lot of PE deals (inc. LBOs and IPOs).
No getting around the fact that it is due diligence. Quite long hours especially if it's crunch time on a deal as you are entirely at the beck and call of the PE firm you're hired by.
Transaction Service Salaries
It's quite hard to get into one of these teams unless you come across as a lateral or have already completed 3 years in consulting or audit.
Base salaries are usually the same between TS and CF and roughly correspond as follows:
1st Year (i.e. first year out of audit/consulting): $75k
2nd Year: $90k
4-5th Year: $110-120k
7-9th Year: $175-200k
Partner: $200-250k base, 7 figure bonus potential
Hopefully this clears things up a bit. Happy to answer any questions anyone has.