Err, this one took me almost a year to compose XD. But its better late than never I suppose right? Anyway, I got this lens September of last year as an anniversary gift from my wife as she supports me (sometimes) in my hobby in photography XD.
I was keen on getting a 24-70mm f/2.8 but its difference in cost over the one that I bought gave me no choice but to get an alternative. I sacrificed a full stop (f/2.8) over a longer focal length but I guess it paid off in the long run XD.
With its superb build, optical and mechanical quality, The Canon EF 24-105mm f/4 L IS USM is undeniably one of the best all-around lens they have ever built. Though I wanted the 24-70mm f/2.8 more, its cost made me choose this one over the other as my all-around lens.
As it also belongs to the L-series, the Canon 24-105 has answered every need that I wanted. As the 24-70 has no IS (Image Stabilizer), the 24-105 gave me some leverage given the fact that I have a shaky hands especially when holding heavy objects.
I never regretted my decision on getting this lens (well....) as I consider it as my L-Kit Lens XD.
As of writing, I've been using this lens more than my 50mm f/1.8 XD
You may want to read a full review of the Canon EF 24-105 lens here, or you could simply google it =P