Yes it was terrific - it couldn't go far wrong with 2 such great leads in John Simm and Philip Glenister. To be honest I hoped they'd wrap it up in just one series but am looking forward to the 2nd. They couldn't really have spun it out much longer than that, given its (apparent) in-a-coma premise.
I don't see how the dual ending thing (if true) is a ruse to prevent spoilers in the press, though. If there was a leak, they'd simply be reporting two possible endings instead of one. I think it's a bit gimmicky and if I were being ultra-cynical I'd say they were hoping to boost dvd sales by including the alternative ending as an extra. If you've got strong writing, you should have the conviction in one chosen ending.
I get irritated by this whole US remake thing. It's as though they can't just appreciate a good quality import - no, they have to make one of their own. Grrrr!