Having logged many hours with both, I wholeheartedly disagree, provided it's a large enough screen. I can see where the 8" model could be hard to manipulate.
I've become spoiled. With an iPod touch, touchscreen nav and audio in my car and the 5212, I can't go back. (I have keys on my Blackberry though, because I don't think the BB Storm quite hit the mark)
If fact, I find myself tapping on non-touchscreens because it's become so natural. Also keep in mind that Garmin makes use of nearly all 70 square inches of display for the virtual buttons. So they're not only large, but predictable. Compare that to ever-changing softkeys that have to contend for 2, maybe 3 edges of the screen probably totalling 18 sq inches. Those change all the time, so the user has to study the screens and remember the location of more functions. In reality, "feeling" your way to a rubber softkey does little good if you have study the screen to determine the current contextual function.
I'm not sure if I can even describe it, so maybe it's best to mention that NO-ONE has used my 5212 and walked away any less than amazed. I wouldn't trust the WM salesguy with this much of an investment. Real-world experience is needed on this one.
I don't get the fish guts argument either. I've never hit ANY electronics with guts on my hands, but if I were to do that, I'd much rather touch a big flat screen and wipe it off later with a single swipe than try to extract scales and grime from deep inside the crevices of buttons.