"Offense wins games, defense wins championships" is an often repeated phrase in the sports world. Whether or not it's really true is debatable. At any rate, we have a similar phrase here at Bitglass - "features win deals, architecture wins markets."
All too often, you'll hear the vendor community touting their latest and greatest feature as a means of attempting to differentiate themselves versus the competition. "We support over 1000 applications," says Vendor A. "Oh yeah, well we support over 1100 applications," counters Vendor B. What do these feature comparisons accomplish? Usually very little. Vendor A will go back to the drawing board and find a way to get to 1200 applications, and the battle for the lead goes on and on, despite the fact that you, the customer, care only about the 15 (as an example) applications that apply in your environment.
Don't get me wrong - bells, whistles, gadgets, and knobs are very important - after all, you wouldn't be looking at solutions if you didn't already have a specific set of needs in mind. Features fill those needs.
What really gives you a solid idea of whether or not a product is going to meet your needs into the future is the architecture. The critical choices vendors make on architecture are typically based on a couple of key insights and mindsets, and once those choices are made, they are usually very difficult to swap out.
The moral of the story? When you're evaluating new products, you need to pay attention to feature set, but don't forget about the architecture and the underlying philosophy behind why the vendor has built the product. Press vendors to explain to you not only what, but why and how they do the things that they do. What you'll typically find is that some vendors have taken the time to build a scalable, expandable architecture that will meet your needs into the foreseeable future. Others are in a race to build the biggest possible datasheet in the shortest possible time.