I've placed 6 different orders from Rosegal over the last 2.5 years. The following is my honest, objective opinion of my firsthand experiences. Contrary to some of the other user experiences I've seen on here, I have not encountered any issues related to deception, nor do I find myself smelling of petroleum.
I would say that the quality for the price-point is excellent. Comparable to H&M and the like. The dresses that I've been wearing for 2.5 years now aren't showing signs of wear. Nothing that I've ordered from them has shrunk, stretched out, or faded so far. Nothing has bled in the first wash either. Some items have had a slightly different color than I expected, or were thinner than I thought they would be (for one sweater), but I would say that's going to happen any time you're buying online. Overall my experience has been extremely positive.
I have found shipping speed to be variable, though generally in their stated timeline. I've never been in a rush for anything, so don't mind if something takes a little longer than expected. It is shipping from China to Canada, after all. I have never paid for shipping, and I have found most orders arrive in 2-3 weeks. If they don't have everything ready to go right away, they will make partial shipments. I've had items come as quickly as 2-3 business days (!), while one item is expected to arrive a week from now, after ordering 2.5 months ago. That was an order placed just before the holidays, though, and there were some hefty delays from that.
I made a mistake on one of my orders, accidentally ordering two of something, and the customer service response was incredibly fast, helpful, and pleasant. Everything was resolved before it shipped about 2 days after placing the order.
I've never tried to return anything, as there has only been a single item here and there that doesn't work for me (less than 10% of what I've ordered), and the cost of the item is on par with the cost of shipping it back. I just give those away or donate them.
In terms of fit, I have altered probably 30% of the items I've ordered, because I have the ability to do so. My chest is large enough to cause problems with sizing, so I often need to bring the waist in or add darts to the bust. I usually know before I get them which ones I'll need to alter. I have generally found the sizing to be true to their size charts. They vary with each item though, so you need to look before ordering.
I first found out about Rosegal from a trendy little boutique in Toronto while visiting; I obsessed over a couple of dresses that were just one size too small and asked about ordering a different size from out of province. The cashier was kind enough to tell me their source, and I will forever be indebted.
Thanks to Rosegal, I have "found my voice" through my clothes and completely overhauled my style. I have bought over 20 dresses from them (mostly vintage style and still keep buying), and every single time I wear one, I get compliments: family, coworkers, friends, and random strangers. Well into my thirties, I finally have a wardrobe that is entirely unique and reflects my personality (and is age-appropriate!). I tell everyone I know about them. They list complete measurements for their items, which makes ordering the right size and the right style really easy.
I heartily recommend Rosegal to anyone and everyone.
As a side note, I get very annoyed when reading complaints about customs charges. These never have anything to do with the seller - it is your own government placing taxes and duties on items you are importing from an international seller. It is your responsibility as a citizen to know and understand your own country's laws and regulations.