I like Timeless and I would recommend sticking with it as it gets progressively more convoluted as it improves. If you like sci-fi then I would compare it to the following: far more serious than Sliders, not as fun as Dr Who, not as good as The X Files. Various episodes feature lots of nods to other sci-fi shows and movies. There's an ongoing subplot, that becomes more of the main plot, which tries to be like the conspiracy theory arc in The X Files but lacks the slow-burning subtlety to be impressive. There's a definite hint of Han Solo and Princess Leia between two of the leads. Some of the episodes feature some pretty impressive historical re-creation for a weekly TV series and there is an attempt, albeit fairly superficial, to address societal issues such as racial segregation. On that note, it is pleasing to watch a mainstream show with a cast that's more racially diverse than many similar programmes.
Series 1 highlight: Atomic City - Frank Sinatra performs at Las Vegas in 1962.
Time travelling team go back in time chasing another time traveller who is meddling with historical events. Not very engaging. Bad acting/casting perhaps. Lacking in humour or any kind of charm. Gave up after 3 episodes.