Speaking as an enterprise cloud user, there is some truth to that - but not enough. Let me start by saying my company does business with all these companies (Amazon, Microsoft, Google, IBM, HP) and we value our partnership with all of them. But from an "enterprise cloud customer" point of view, they all have their challenges.
With Google, it depends on what you mean by "cloud" of course... Google Apps is industrial strength, but Google App Engine is not, it's more of a cool tech toy, we only use it for non-mission-critical services like our public health dashboard. They're just feeling their way through how to do enterprise sales; I'm a techie and even I thought the presentation they came in and did for Google Apps needed to be a lot more polished.
Amazon AWS has great technology and a great service. We host some of our paid SaaS applications on AWS. Dealing with them as an enterprise customer can be very frustrating. Getting a sales rep in the first place and paying with a PO is doable once you figure out how to get through the wall-of-robots, but even my Amazon sales rep has started trying to steer me to an Amazon reseller when I want to do "fancy" stuff like prepay, or get flexibility with reserve instances, or whatnot. (The inflexibility of reserve instances, and my inability to even prepay or get any kind of discounting, is extremely unhappy from an enterprise customer POV). But, they have the best cloud tech, so we deal with that. They are also not prepared to pursue or take advantage of more high level partnerships; they seem to be very intent on staying a focused utility supplier and don't want to entangle themselves with anyone (not saying that's wrong, just the way it is).
Microsoft Azure has an up-and-coming technology that's a lot better than I expected it to be (I'm an old UNIX/open source guy). We are moving towards hosting some of our paid SaaS applications on Azure. They are... Kinda easy to work with from an enterprise point of view, at least they have the financial mechanics down. You have to deal with "Microsoft Messaging (tm)" and their unending efforts to convince you and your management that everything would magically work if only you'd just rip out every piece of technology you have and replace it with Microsoft technology. The unending cross-selling, jockeying for negotiating position behind every single phone call, etc. is very tiring from a technical staff perspective. And they admix marketing message with technical documentation to the point where most people I meet are confused about Azure's actual technical capabilities.
We talked to IBM about their cloud offerings. IBM is "enterprise friendly" in a certain sense - they can talk high level partnerships and such. They do try to sell you millions of dollars in services all the time, and we're more of a do it yourself company, so that doesn't go over well here (some companies seem to take joy in handing over briefcases of cash for work a single $75k/year sysadmin could do, but we're not one of those). And their cloud offerings are still mostly in the planning stage, or "we'll build something out for you for those millions of dollars in services." We ended up not piloting anything on the IBM cloud because at the time it wasn't really low hassle enough. (Approximately the same thing happened with Verizon, though their tech was actually more impressive.) Here I think some of the "enterprise focused" companies don't understand the value prop of cloud to us enterprises - we want less hassle as much as the startups do. If I have to put together a 12 month engagement plan, it's not "cloud", it's traditional IT outsourcing.
HP has no real public cloud offerings. If you go click on their "Enterprise Cloud" link on their Web site you get links to buy HP ProLiant blade systems and/or professional services. We use plenty of HP software in house, but this is one of the worst cases of just taking your existing product line and slapping "cloud" on it. If "enterprise friendly" means "can sell stuff to wooly-minded execs who have no idea about cloud", it's certainly enterprise friendly. I may be biased because I consider "private cloud" to be basically a big lie, or at best a reminder that in your own data center you should probably be using virtualization and automated provisioning. HP's solutions are quite good for that, but they're not to be confused with what most people mean when they say "cloud."
So in the end, there is currently a mix of companies who have trouble interacting with enterprises in the traditional way but have real useful cloud technology, and companies that work in a more established way but are mainly rebranding existing technology as "cloud" to cash in. This is obviously a continuum with no "right answer", going from "super high tech but you can only pay with credit card" to "$50,000 toilet seat with a 'cloud' sticker on it." You have to decide what suits your needs best (and as an enterprise, it's never just one - I imagine in 5 years we'll be using something sold as "cloud" from every one of these supplier partners). Which of these are "enterprise friendly"? In the end, I buy stuff from all of them, so all of them are. But all of them also have large strides to make - some on the financial and relationship aspects, and some on the raw technology aspects, and both are important to me as an enterprise architect.