Should be another interesting season. Really rooting for Bottas this year, I think he did rather well last year, coming 4th overall in the season in a Williams (beating Vettel, Alonso, Massa, Button and Räikkönen)
Ricciardo will be another one to watch this year. He's really on the pace.
Ferrari have a had some time to develop their car, and with Kimi and Sebastian as drivers they should be in with a better chance than last year and Mercedes may not be quite so dominant. I predict both Ferrari and Williams will be closer to the Mercedes cars this year (and it's been nice to see Williams back up amongst the top teams again after so long in the lower tiers).
I don't think Button or Alonso are really up to the caliber of the new batch of drivers any more, but I am willing to be proven wrong on that.
Anyway, let the KERS and DRS and turbos loose and let the sparks fly!
I think there's a lot wrong with the sport, particularly the tight technical regulations which completely stifle larger technological innovation and inventiveness (and so many technologies banned which could benefit the car industry if they had the scope to experiment and develop them in F1), but it's still worth watching.