On the one hand, compared to Amazon.com, Taobao sounds like a horrible shopping experience. On the other hand, compared to a shuk (or whatever the Chinese equivalent is), it is a vast improvement.
Context is everything.
(1) Shops are absolutely crap scared of a bad review. Shoppers avoid bad reviews like the plague, and there's normally so much competition that you can always find an alternative. The 1 time we gave a bad review, we had a call from the seller within 1 hour offering all manner of things for us to take it back.
(2) Delivery is excellent - next day courier services. Taobao practically revolutionised the postal service in China because the national postal system was so bad. So, 10RMB (around £1) can get you national, next-day delivery for most small items (eg. a small parcel).
(3) The mobile site is awesome, full stop.
(4) There's just so much choice. I can buy official, full price products from the brand (ie, not a reseller, but the actual company), or 2nd hand, or knockoffs. Most knockoffs are clearly marked as such.
(5) Safety - it's not a direct payment system per se, but an escrow service. If you aren't happy in any way with your product, you click a button and the seller gets nothing.
There is aliexpress also which is in many languages.
Taobao has one factor that generally makes it better than ebay and most other online retailers and auction sites: it is the sole source of income for many companies that sell through it. Many Chinese manufacturers are only selling their products through the alibaba ecosystem so they really care about their reputation. That is why they get defensive or start offering all sorts of things to remove bad reviews, because it can shut down their whole revenue stream.