I have mixed feelings on "The Lodger." On the one hand, it made me laugh loudly and frequently. On the other, I think the clueless Doctor schtick that produced many of those laughs was rather over the top, verging on out of character.
The incarnations of the Doctor vary in perceived craziness and how easily they can blend into human society. Eleven is significantly more out there than Nine or Ten, and I can generally deal with that. However, in this episode the degree to which he appears utterly without knowledge of the social norms of early 21st-century Britain (rather than merely not caring about said norms) seemed a bit hard to believe. He spends enough time in that general corner of space-time to know that men don't typically greet with air kisses. Ten (and to a slightly lesser extent Nine) made frequent pop culture references, yet "The Lodger" asks us to believe that the Doctor doesn't remember what exactly football is. What?
My current theory is that the Doctor is deliberately playing up his eccentricities and non-human habits to cope with his discomfort with the scary situation of being temporarily without a TARDIS and having to rent a room. It's only a few steps away from having a mortgage, for crying out loud. The Doctor is reminding himself and everyone around him that he is not going to be staying.
Some things I liked:
-the bits with the TARDIS, especially the Doctor making Amy take two steps to the right in order for the switch to work.
-the Doctor walking to the football game with his tweed jacket on over his jersey. (Also, do I recall correctly that Matt Smith used to be pretty good at football when he was younger and only ended up in acting because of an injury? If I'm not just making that up, excellent use of an actor's real skills.)
-the spinning contraption the Doctor built in his room. Some prop people had fun with that one!
-the Doctor's hypothetical shout to what's-his-name (Craig?) if he ended up bringing home a girl- or boyfriend: "I WAS NOT EXPECTING THIS!" Ha!...And now I want someone to create fanfic where Rose or Jack shows up while Eleven is lodging at the flat, forcing him to use that shout.
-speaking of unexpected things, we had naked Doctor! This fangirl approves.
-This is not something I liked, just an observation, but it seems silly for the Doctor to do the headbang information transfer rather than the quieter mind connection he did with Reinette. Possibly someone decided the intimacy of such a gesture would be a bit much between two guys? That's a little odd for this show, even though S5 has sadly not been as strong about including queer people as RTD's seasons. I guess it's just another example of "The Lodger" playing for laughs above sense. *shrug* It was funny.
-Hey, look, the crack again! Speaking of the crack, was I the only one who was worried last week that when the Doctor and Amy visited the museum after saying goodbye to Vincent for the last time that they would find that the crack had appeared and erased Van Gogh from history?