Martin himself, the character, is Dickens's first anti-hero. He's a charming shit- a type we'll be seeing again as the oeuvre progresses. There'll be Steerforth for instance- and Eugene Wrayburn. These guys all think they're rather wonderful- and have zero self-awareness.
Chevy Slyme and Montague Tigg are Martin's shadow-selves- charming shits who have been found out and rejected by polite society. Martin had better watch out or he'll end up just like them. When he's enjoying writing a character- as with Slyme and Tigg- Dickens lets them run on at the mouth- and say the most preposterous, colourful, surreal things- and it has the slightly counter-productive effect of making his villains endearing.
My first reaction to Mark Tapley was that the character was impossible- and that no such human being could ever have existed- but then it dawned on me that he's meant to be a saint- a secular saint- and saints are one-offs, existing at odd angles to the world- and Tapley's eccentric spiritual discipline- which consists of testing his "jolliness" against the most trying of circumstances- is no more peculiar than the sort of things St Francis used to get up to. Saints are fixated- and can be pig-headed and downright annoying- as Tapley certainly is. He has a snug berth at The Dragon- and a woman there who'd marry him if he'd only ask- but he walks out on them both because he's a man with a vocation. He chooses difficulty- just as St Francis did- and there are times when you want to slap such people round the head and bring them to their senses.
We're nearly 100 pages in and nothing much has happened by way of plot, but, given that plot is rarely Dickens's strong point, that's fine. All one asks of him is that his characters should keep on bumping into one another and new characters should keep popping up- and that there should be a comic or dramatic set piece every so often....