Problems were basically, in order of importance:
1) His hair. Sweet merciful Dionysus, what did they do to his hair? His controlled-chaos Doctor hair is adorably hot, and that same bedhead look would, you'd think, be ideal for Casanova. Instead they smashed it flat across his forehead and gave him a rat-tail. Seriously. A rat-tail. And this was filmed just the other year! Not in 1983! What's their excuse, exactly? Oh, historical accuracy, I suppose; pigtails were common enough on men; but that doesn't mean you have to do it when it's going to end up looking like that. Gah. They're making me overuse italics here.
2) His eyes. Blue contacts, presumably to match Peter O'Toole's eyes (as Casanova in later life), were not too bad as contacts go, but they're a letdown to those of us who happily submerge ourselves in his natural soulful brown eyes, episode after episode, on Doctor Who. Also, in some light conditions the blue came off really unnatural. Groosalugg-ish, almost.
3) No one else looking very good either. Everyone seemed to suffer from bad complexions and dull features and unflattering costume colors. (I'm not even going to inflict upon you the awful aquamarines they kept throwing onto Tennant.) The only one who looked lovely throughout was Rose Byrne, and she wasn't really even a love interest.
4) Total lack of chemistry or affection in most scenes. Compared to the Lasse Hallstrom/Heath Ledger version, which managed a great deal of cheeky charm, this was all sleaze and cheeze.
5) Cheesy editing. Mugging for the camera? Having his clothes fly onto him by themselves under a spotlight? Awkward freeze-frame of him reading a letter while dancers blur past behind him? Bleh. Just didn't work for me.
I don't normally bother with negative reviews, but this was so egregious I had to mention it. It's a sad thing when in the middle of a crush on Tennant, I can still find Heath Ledger a hotter Casanova. And this one gets better reviews on Amazon than the Hallstrom/Ledger one! What gives? What am I missing here?
Mystified but still not blaming David Tennant since it really wasn't his fault,
P.S. I swear I'll post about something un-Tennant-related next time. Really.