I do admit that Sips has been rather lucky in avoiding most wars, but at least he has a plan. He's going for a cultural victory as France. I do not know whether he knows this or not, but eventually he'll ruin Duncan's game with ideological pressure. I actually see some improvement from Sips in contrast to his previous games as Venice and Netherlands, especially Venice, where barbarians pillaged all his improvements and he didn't do anything for about 100 turns. This is in contrast to Duncan, who has a lot of potential but is ignoring a key element in the game and it will do him over, unless he chooses the same ideology as Sips.
Lewis has been very unfortunate with a tundra start, but he has actually caught up rather well. However, to add to my criticisms, he settled a third city right in the midst of tundra just for a luxury resource. It might keep the barbs away but it's costing him science and happiness.
If they do continue the game (unlike the previous series where they just stopped and declared Lewis the victor on score about halfway into the game according to number of turns), it will be between Duncan (science), Lewis (science), Sips (cultural) and Rythian (diplomatic). Sjin, to me, seems somewhat crippled in this game, along with Pyrion, who is still expanding even though he's got the lead in the score. I could be wrong; either of these players could catch up late in game, but I see Sjin's general influence as weak and Pyrion's strong military influence decaying by tech as he has to focus on defensive manouevres until Lewis and Sjin make a mistake. Also, I hope Sjin knows how to win a science victory and use airports too.
I also have to add a general criticism, but I don't blame them too much: in multiplayer, spawned barbarians move straight away in BNW, but in SP, this is not the case. The implications are that a barbarian could appear 2 tiles next to your worker (assuming that there is a flat unmarshed tile in between) and take it before you could act. Furthermore, they complain a lot about barbs but they don't think ahead: you take out a barb encampment, another one is going to appear nearby unless you have the wild territory revealed by patrolling units.