I've been doing it for years (a little over 8 now) and still love it. Most of the time though now unless I'm going somewhere that I know has required units/whatever or there'll be something of particular interest, I don't write everything down. Logging moves, of course they get written down. I used to spot stuff for the year, just out of interest to see how much I saw in that year, but after a while that got a bit dull so I sort of dropped out of that. It wasn't helped one year when I lost my book on an HST so lost all that valuable data, yes it was valuable to me!
I might do stuff for the year next year, just for fun, but we'll soon see. Certainly I'll be trying to get all of the LM 170s and ATW 175s for haulage in 2012, since they're local and I use both lots regularly.
At the end of the day, if you're happy doing what you're doing then fair game. Spotting isn't for everyone, nor is bashing. Bus spotting and bashing is much like, not for everyone. Nor is aircraft spotting or bashing, but I enjoy rail, bus and air bashing/spotting. Not bashed a plane as such yet, no records of those I went on years ago sadly. Hopefully changing that in 2012...As you can see, I've got loads of interests, just not 'normal' interests!