Oh, you've probably bought it by now, but anyway...
It's easy to clean, v shiny wood so even cement-like porridge or simlar comes off with a bit of a rub. Quite a lot of holes for adjusting the seat and footplate height means that stuff can get stuck in there, but otherwise not too many crevices. I'd ditch the cushions asap, though - although they're washable, mine went a bit sort of lumpy and mangled looking after a while, and they needed washing A LOT as DS1 was so messy.
We haven't used the harness for ages, but that obviously gets quite messy, too - is black, though, and not too hard to clean - we used the wooden bar for as long as possible, and then just had the chair pulled right up to the table so didn't need to use the harness much at all. It was only after he was about 18-20mo that DS1 was able to push the chair away from the table himself, and then he didn't really need the harness anyway.
Lack of a tray was never a problem, and DS1 is still resplendent in his Babydan at 2.8 - DS2 has a clip-on-to-the-table chair, as we don't see any possibility of ousting DS1 from the Babydan, he loves it! We tried a booster seat on one of our normal chairs in preparation for DS2's weaning, but DS1 disdained it .