Briefly, on Agile
Agile is a process for managing software development. If you have a great team of smart people who communicate well and trust each other, they can use agile techniques to release lots of small iterations on a software project very quickly. This pattern of software release is often useful for startups. None of this is in dispute.
The problem is that with its rise in popularity, it has been both misunderstood and over-applied. If you have a good software team you can use agile, but if you use agile you will not automatically get a great team. If your team members communicate well and trust each other they can use agile, but if they communicate well and trust each other they could use any other methodology up to and including no fixed process whatsoever, and be equally successful. Agile changes your release pattern, not your people.
Bottom line: great teams produce great software. Great teams using agile release software every two weeks. Bad teams will produce shitty software. Bad teams using agile will release shitty software every two weeks.