After two years spent predominantly competing in the World Rally Championship, Raikkonen returns to F1 with Lotus, formerly known as Renault.
The burning question is which Raikkonen will be on show - the one that won the world title in 2007, or the one that fell out of love with the sport in 2009?
Renowned British driver Watson, who started 152 races for Brabham, Surtees, Lotus, Penske and McLaren from 1973-85, feels Raikkonen will find it hard, as has been the case with Michael Schumacher over the last two years.
"I'm a big Michael fan, and I had hoped he would win a race, but it has been a struggle for many reasons, and I'm sure Kimi will have to deal with those reasons," said Watson.
"Tyres, aerodynamics and technology have moved on since Kimi was last in the sport in 2009, so it will be difficult.
"But Kimi is the kind of guy who is ostensibly laid-back, so will take it in his stride.
"There's probably a lot he wants to prove, but will do it in a Kimi way, so it will be interesting to see how he gets on, certainly in relation to Michael.
"But he's at least joined a great team, and I would like to believe they will return to the level when (Fernando) Alonso won his world championships there (2005 and 2006).
"I'd love to see them winning again, and to see Kimi Raikkonen in a competitive Formula One car will be very exciting.
"I just hope his commitment will be at the level when we saw him at his best in his early days in Formula One, and not as in his last season with Ferrari."
Raikkonen's return means there will be six world champions on the grid for the first time in F1 history, the Finn joining Schumacher, Alonso, Sebastian Vettel, Lewis Hamilton and Jenson Button.
Watson, however, is not expecting this year's title winner to come from outside that pack.
"With six world champions on the grid, you couldn't ask for better advertising," added Watson.
"The usual suspects are the top four teams, and they are there to be challenged by the likes of Lotus, maybe Force India.
"But the resource the top four teams possess, not just financially but human and technological resource, is at at a level that makes it difficult to challenge when coming from behind.
"You may need a superhuman as part of one of those teams, and whether they have a superhuman is hard to tell.
"At Force India they've replaced Adrian Sutil with Nico Hulkenberg, who I think is outstanding.
"Whether he and Paul di Resta can be combative enough to push Force India further up the field, that's going to be one to watch.
"But those two young guys are potential future world champions that we need to be aware of, to monitor their progress.
"But whether the team supply them with the equipment over 20 races, that's a big challenge for Force India."