Heh, that's my point. Bond movies never feel like continuations of other Bond movies. The lack of gadgets further made it feel less "Bond".
The last Bond movie I saw was "The World is Not Enough". So I can't comment on the ones since then. But prior to that movie, there is absolutely and unquestionably a unifying theme throughout the series, in much the same way one can recognize a Sherlock Holmes story based on the character development, the plot, the narrative, the setting, etc., regardless of whether reference is made to past stories.
Also, the gadgets thing is obvious. I don't know about quantum of solace, but for crying out loud. They have a character devoted to introducing the latest Bond gadgets -- Q. He appears in every Bond film I've seen (pretty much every pre 2000 Bond movie).