Up until recently I had both a 350 and a 650 in the house. The 350 was for my Mother in Law and after setting it up for her I gave it to her this last weekend. I agree with the others on this thread--the smaller 350 works great, and I wouldn't miss the extra size. I really was tempted to keep the 350--the small form factor would be so much more convenient. Right now I'm using a large purse so my 650 will fit in it just fine--but as doreenjoy points out the 350 will fit in much smaller purses/carriers.
The only caveat--if you're going to attempt to read PDFs (especially those that are technical in nature) the 350's screen probably is a little too small.
dordale