From what I have seen of them they don't actually corrode like the old outboards did (especially Suzukis) but they do get a funny look on the paint on the aluminium bits. I think a lot of the critisism came from them using automotive parts instead of stainless parts under the cowl. These are supposed to be things like clamps, saddles, dipsticks and things like that. Not sure if this is B.S. or not but I think they have got there act together a lot better and the motors coming out now have addressed some of these problems.
I would still buy a Honda if the price is right. Motor selection comes back to power to weight ratio. You also have to throw c.c.'s into the equation as well. You can't pick a motor on brand loyalty, you just have to pick the best motor for the horsepower you are after.
I have owned a Johnson (OMC/Evinrude), Merc (same as Mariner) and a Yamaha. I nearly bought a Suzuki 4-Stroke 2 years ago and it was only its weight that turned me off. I could quite easily buy a Honda tommorrow if it was the right motor for the job.