I test drove both recently and I loved the spec-V. The engine is torquey and smooth, the handling is nice and the car is just packed with value. It's actually cheaper than a P5 in Canada, when you add A/C to the P5, as the SER comes with it standard.
I really liked the interior styling too(2003 have black on grey seats, much better looking than the 2002s!). What I didn't like about it was the massive amounts of tire noise, the harsh suspension and the lack of ABS. The Protege ES I drove handles just as well as the spec-V with a much quieter, more pleasant ride. It also feels more homogenous, the spec-V feels like a sentra with aftermarket add-ons. The styling, though aggressive, is kinda busy, while the protege I find is just the opposite... Clean and simple. Some may call it bland, but I like it.
I also much prefered the braking performance of the protege, and to me that is just as important, if not more, than sheer power.
Yes the Protege ES/P5 can't compare performance wise, but they are just as fun to drive, and make better commuter cars IMO.
Seems a lot of people here are either brand nazis or just plain jaleous of spec-V owners... Grow up, no need to hate