After several years of agile and scrum hype around, I'd expect the first well-known reactions from "bullshit!" to "magical!" to be gone and I should be able to find some really elaborated articles that question the highly praised benefits of those modern management techniques. But I don't.
Aren't there any? Is scrum really that great? Is there a conspiracy going on?
No, scrum isn't that "great." It is just another framework. It may or may not work for you.
But the reason I think it hasn't become a "Mac vs PC" war is the agile community knows that. There are few people in the agile community that will say agile is the one and only way. Most of those don't tend to stick around long as it pretty much flies in the face of the tenets of agile.
Much of the agile community is in the camp of "give it a try" and not "you must convert." A low barrier to entry, and a generally welcoming community means less conflict.
Me personally, I've always maintained it is just one of the many tools in my tool box. I find I reach for it more and more, but it still sits in the same box as the PMBoK, Conflict Management training, Manager-Tools, Customer Service Training and other tools.
I should be able to find some really elaborated articles that question the highly praised benefits of those modern management techniques...
Unfortunately, Scrum has nothing to do with management techniques. It's a framework which tells you how to do the software development. Regarding managers, it says that a good team doesn't need managers, it needs people who keep away those who want to disturb the team. I have no idea why people thought that managers would let themselves be put aside.
Is there a conspiracy going on?
My version: The original idea of Scrum was great, but after that came the consultants and turned a good initiative into business. You can attend to courses and workshops for a lot of money, but they won't really help you with the challenges of the job. Until there's money in this business, you won't read any elaborated article about it.
Is scrum really that great?
My main problem is that Scrum is taught as the ultimate solution for every possible problem in the software industry, but there isn't a good way to scale it, use it for maintenance or handle cases when team are changing often. It says that the teams should be kept together almost forever, or if you test well you won't need maintenance, etc. Tell this to you boss and there is a good chance that he'll finally have a good laugh. It is unrealistic.
I can understand that an organization wants to change because it feels that things could go better, and thanks to the hype, they'll find Scrum. Instead of trying out Scrum they should find out what their real problem is.
Nevertheless, it is a good thing to have a look at successful companies like Fog Creek, GitHub, 37signals and find out what their secret is (none of these companies do Scrum or follow any other Agile framework. They do certain techniques, but it is a different story).
There's a well-known Ken Schwaber quote:
Scrum doesn't solve your problems; Scrum exposes your problems.
He's exactly right. You still have to find and fix the problems that are keeping you from delivering high quality software more quickly.
I've been in this business for three decades, and have managed teams for almost two decades, on and off. I've gone in and fixed a couple dozen companies in the past six years, using a combination of Scrum and Kanban. Lean/Agile approaches to software development work very well, if you understand the underlying philosophy. If you don't, if you just proceed with a 'cargo cult' rote form of Scrum (or another Lean/Agile approach), you will not get the results you're looking for.
If you want a specific criticism, then let's look at the most common failure mode for Lean/Agile? When an organization (and specifically its leadership) is unwilling to acknowledge and fix the problems that this approach exposes. In fact, this is the only failure mode... and it is a universal failure mode.
There are many well-articulated arguments against Scrum and some other answers have pointed those out, so I'll leave that part of the question be. As for Agile, I think the big thing you have to consider is that Agile is made up of value statements, which are inherently very difficult to argue over.
Let's take the first value as an example:
Individuals and Interactions over Processes and Tools
This means that we value people and their conversations and collaboration with other people. When we use processes and tools, we try to make sure that the ones we select or build improve people's ability to work together.
Now, you either agree with that or you don't. You can't really argue that forcing people to use a tool that causes them to have trouble communicating with their colleagues is better than one that streamlines communication. If your job simply requires a warm body that follows a set process and you haven't automated that function yet, then sure, Agile isn't for you, but we all know that - there's no reason to debate the point.
Now, of course, anything can become dated. There was quite a bit of conversation a little while back about updating the 12 Agile Principles because some of it just doesn't make sense anymore. For example, referring to delivering software every couple of weeks to a couple of months as delivering quickly is very dated. Many companies deliver production software multiple times per day and people delivering every few months are well behind the curve. But that points us to the other reason you don't see many debates: Proponents of Agile are a lot faster at pointing out flaws and pushing to fix them than opponents are.
Agile has changed a lot in the past 15 years and as long as it continues to, many of the arguments against it are left in the dust as people practicing it find the weak points and keep improving them.
That's a very good question indeed, and no: Scrum is not that great, if you take it as a bullet-proof, cheap, one-size-fits-all way to let your team/company magically solve their problems... it is great if you know when, why and how to use it.
That said there are several critiques out there that might be interesting for you. Some of them are not inherently related to Scrum, but nevertheless question some knowledge that in the Scrum world is taken for granted or "trusted" more as a dogma than as a verified experience.
A good book on this is The Leprechauns of Software Engineering
But you can also have a look at:
Hope this helps :)
You might want to look at Bertrand Meyer's book Agile!: The Good, the Hype and the Ugly, which, as the title says, deals with the good and bad of various agile methods. I can't summarize the entire book in an answer, read it for yourselves, but just in very large strokes:
The good:
The bad:
