I have been attending Pubcon in Las Vegas every year since 2003. I have only missed 1 or 2. Also, Pubcon is the only conference I have attended.
What I'd say about Pubcon is that I look forward to it every year, year after year. It's a busy 3-4 days conference. Usually 6-10 sessions running concurrently and the topics vary from On-page SEO, Off-page SEO, Paid Search, Affiliate, Conversion Optimization, Social Media and so on. There are usually around 100+ sessions in total to choose from.
Overall a great event to attend.
What will you learn ? Well, that's a tough one to answer. Usually I don't go to conferences and expect something to learn other then meet a lot of nice people in different industries. Sometimes you talk to people, hear out speakers and see them talk about specific strategies they use or specially the tools. I love the tools part. There's always something new to learn in the SEO Tools area. Other then that, talking with people and attending sessions kind of gives you a very broad/but in-depth overview of where the industry is moving, whats going on in the world of search.
I also have Mozcon/Distilled/SMX Advanced/SES to the list of conferences I would consider attending based on timing and budget.
I hope this helps.