I think it is the Jar Jar on crack thing. I liked Tennant because, while he was a bit quirky and fun on the surface, his Doctor was portrayed as extremely intelligent and quite somber at times. Matt Smith plays the role as a wild eyed kid giddily going off on all these adventures without putting much thought into it until his companions get f-ed over time and time again, at which point he feels bad, gets serious and rescues them, then goes back to the goofy excited kid dragging them into yet more danger.

While Tennant's Doctor was quirky and a bit odd, Matt Smith's is over the top goofy at times.

But I am an Americano, so I don't count. Going back and watching some Tennant episodes with my friends, I had forgotten just how much I liked him as the Doctor.