To say the least, my eyebrows were raised and my ears were perked when I read Doug Ware's article "SharePoint 2010 Sandbox Solutions are Bad". If you are unfamiliar with what a sandbox solution in SharePoint 2010 is, I would recommend reading this article here.
His basic complaint about sandbox solutions is around the restrictions they pose. For a moment let's consider what sandbox solutions give you. Sandbox solutions finally give you the ability to deploy at least some percentage of your code, with confidence that they wont kill your server. You as the architect can decide that percentage to be zero, or 100%, or some mixture of the both.
So if you think sandbox solutions suck, why not just go with 0%? So how can something extra be bad!??
Now let me talk about why I don't think I will ever see a project with sandbox solution being used at 0%. Or at least not a project that I will be a part of. Farm solutions and custom code is the number one necessary evil on SharePoint projects. It is also the number one issue that causes problems and updates. And it is also the number one issue that causes contention between IT Pros and developers. Sandbox solutions solve all of those problems.
In return you do give up some freedom! Freedom that Doug describes as his complaint around the height of those walls! My feeling is that there's been plenty of thought given to where and how those walls have been drawn. And where you do need to cross those walls, you do have the flexibility of writing of full trust proxy, or a custom WCF service. So again I don't see where the problem is!
Microsoft is giving you an arrow in your quiver to establish more control on your project, to guarantee better health of your server, to reduce contentions between IT pros and developers, to help ensure that your SharePoint server will upgrade easily in the future.
So here is how I see it! Complaining that sandbox solutions are bad, is a bit like complaining that the lock on your door causes a huge inconvenience when walking into your house. I mean what a pain it is to bring the keys out of your pocket, an unlock the door before you can get into your own house?
You know if you think that lock is such a pain in the donkey, don't use that lock! Write a solution validator to disable all sandbox solutions. I for one do intend to use that lock, and I intend to use it well.
I don't think Sandbox solutions are bad. In fact, they are a very welcome addition to SharePoint 2010. Not only do I intend to use it, I intend to grill anyone who insists on not using them. Consider yourself warned! :)
Update: Eugene and I are having a pretty good discussion on this on facebook too. Feel free to chime in.