In an unusual twist the only other Lego game I put a lot of time in (so far) was Lego Pirates of the Caribbean. It was bought as a gift for someone and the story is quite complicated and kind of sad.
Anyway this is in October 2011 shortly after I got my 3DS and I haven't played it since April 2012 (3DS Activity Log) so you'll have to forgive my memory. I played for 13 hours.
For Lego City 3DS I played for less than a month from late September 2013 but put in over 20 hours.
Based on what I remember of Lego Pirates the levels were super simple and narrow. Extremely linear with a a lot of fight some guys, search some spots for blocks then build a thing.
Can't comment more than that, sorry.