Brett makes great points why he, one of the modern era's greatest plain text heroes, uses Evernote. In short, Brett uses Evernote because it’s useful—not unlike Brett himself.
I’m very much a plain text nerd, too. I can hardly go a week around here without extolling nvALT, Markdown, and other plain text tools.
Plain text just plain rocks. It's not a panacea, though.
I can’t store PDF camera manuals in plain text. Or my medical insurance cards. Or photo scans of handwritten notes. Or photos of potential Christmas gifts. Or audio notes.
Yeah I could put that stuff in Dropbox. But Dropbox doesn’t OCR images for me. Dropbox doesn’t give me a single search field on my iOS devices. Dropbox doesn’t have a single point of entry on my iPhone for every kind of data that Dropbox can house.
And Dropbox, to me, just lends itself more to folder-based organization. It’s not immediately obvious, for example, where to put a photo of a credit card brochure containing information and phone numbers for roadside assistance. Yeah, I save crap like that.
Evernote is a house for the randomly useful, but it’s not an everything box. At least not for me. It’s simply a very well-designed niche tool for capturing and storing non-plain-text information that I want to retain.
Evernote makes my life easier: When my wife calls me from the pediatrician’s office and needs to know whether well child visits are covered under our new insurance policy, I’m glad all I have to do is make a quick text search on my iOS device and find the answer in seconds.
I think the mistake so many people make with Evernote is the same mistake people make with Microsoft Word, Microsoft Excel, and other apps that have the potential to do everything.
Don’t approach Evernote with an all or nothing attitude. Instead, 1) look for specific ways that Evernote can make your life easier, 2) use it for those things, and 3) STOP.