I'd been looking forward to "Heart of Glass" for ages, and it definitely lived up to my expectations. The first case, with the girl in the bathtub, kept me guessing right up until the end. It was really cleverly done, and it was certainly an original way for the girl to die. I also loved (as did many) the whole "DL" thing on the mirror. If they're not even going to bother to mention Lindsay (which is really annoying) then minor allusions are the next best thing. With the second case, I loved how the sister was at first believable as a sane person; she did just seem shaken up about her brother's death. I must admit, the first time I started mentally implicating her was after the passed the lie detector test. Something about that made me think she was guilty, the way the questions were phrased and answered could have been truthful but not really turthful, if that makes sense (which it doesn't.)
Being a Mac/Stella shipper, I didn't like all the Mac/Peyton moments. It's good that they finally showed the relationship to the others, because I think it's more relaistic (and I laughed at the expression on Danny's face!) but I still think the chemistry between them is off.
I really hope Stella is not HIV+! I think it was done quite well, showing Stella's panic and her determination not to let Sheldon touch her, but I really hope we get some continuity in the months util we get the results. And she should tell Mac, for sure. Actually she should have told him in the first place.
All in all, great episode!