I had a wall of text ready - basically my entire ordeal so far, but I decided not to post it. I guess this is not the right thread for it either.
I still haven't received a tracking number for the shipped wheels, even though Rennen had sent me several e-mails on Thursday and Friday, saying they're going to be shipping the wheels on Friday. In the two months I've been dealing with them, I wouldn't say I was surprised.
Their customer service really is horrible. Whether that is due to them being extremely busy or they just don't care, I cannot say. Might be both. The two employees I've been communicating with (sales guy and manager) both seemed very helpful and caring, but the amount of missed commitments and empty promises I've gotten from them cast a very big shadow on their initial appearance.
Will I buy another set of wheels from them? Probably not, unless I really don't care when the wheels will be ready and I'm OK with getting close to 0 updates from them on the status of my order. One thing I hate most about people I'm doing business with is not standing up to your commitments/promises.
If you're OK with waiting 2-2.5 months for your wheels and don't expect much communication going on, then go for it. My advice is also to go through a reseller of theirs, not to buy directly. They're not supposed to sell to end customers anyway.