I began using a Moleskine notebook one year ago. It's a relatively large one (5 1/4" x 8 1/4", or 13 cm x 21 cm). I use it for everything-- work, personal, photography, ebay purchases, phone numbers, email addresses, etc. The good thing is that I know that's where all my notes are. One of the bad things is that it sometimes requires multiple serial searches to find what I'm looking for.
I'm a little disappointed in quality, however. I've used about three fourths of it within the last year, and the cover has cracked along the crease of the spine. I expected it to be more durable. I may return to my previous favorite-- ruled composition notebooks. The taped spine seems to hold up better.