I played Yakuza 1 from start to end, I didn't have much of an attention span at the time so I enjoyed beating on various thugs but couldn't follow the story very well, I snapped up 2 when it came out, unfortunately it took so long reaching these shores that I'd already upgraded TV and console by then, it sat abandoned on my game shelf for months.
In november last year I purchased Yakuza 3, used for £15 but with it's redeem code unused, I placed the game in my drive, downloaded the DLC and ran it once, I watched the recap for 1 and partially because I skipped over 2 altogether, but I haven't played it yet, in fact in Jan I sold my copies of 1 & 2 partially hoping that they'll get the HD compilation treatment some day.
Now 4 is out.... I downloaded the demo at the weekend, played it yesterday and loved it, I'm all set to begin my Journey in 3, even if it's slightly watered down. ( heard people in america created Japanese accounts to go on PSN there and download the additional content but it seems too much effort)