He really is excellent. Remember how he played against the Raiders despite a less than stellar supporting cast. If they can get 4 years out of him, losing the bulk of 1, when he’s in his prime they will be laughing.
Sorry to disappoint any Browns fans here, but he is not all that. As someone who follows the Texans I have seen all his games as a pro and aside from looking great in his first season he has flattered to deceive. In countless games he puts up most of his yards late in the game when the game is already lost against prevent defences, I lost count of the number of times the Texans failed to score in the first quarter or even the whole first half. You might say that is because he didn't have a good team around him, but apart from his last season at the Texans they did have a decent team.
Then you have to question his character. Regardless of his 'extra curricular activities', he seems more about himself than the team. The whole sweepstakes to sign him was very strange. He contacted the Falcons himself to ask them to bid for him, they were not in the race until then. So you would think he would pick the Falcons. Instead he flirted with them, and then went with a team he had already said were out of the race, the Browns, because they came back offering the most guaranteed money. So he went with the guaranteed money and in doing so ruined the Falcons relationship with Matt Ryan, leaving the Falcons without a QB. Supposedly the Falcons were the team he grew up supporting, and he screwed them over.
If I was a Browns fan signing Watson with all the controversy around him would be a win the Superbowl or bust move, and even then it would be a tainted victory. Personally for the reasons above, it is not impossible due to the great roster around him, but I would be very surprised if they win or even get to the Superbowl with Watson. They mortgaged their future for him and the roster around him is going to get gradually worse over the next few years.
And on the subject of his antics, he still says 'I did nothing wrong'.