Motor smell
I bought my Sirena new, and I have to agree it had the worst "new motor" smell of anything I have ever purchased. I found using the fragrances helped mask the odor, but it took a good year before I didn't wonder if the thing was burning up inside.
Two years later, I have had a couple problems. The power nozzle had difficulties with stopping. It was found the fuse holder was broken. Sirena sent me a new one with instructions. It was about a 10 minute repair.
Second one was the very delicate, and brittle latches on the electrified hose. If you break one, which is easy to do, you have to replace the entire hose.
I don't see Sirena up to the quality of a Rainbow, but then again, it cost me a fraction of the price, it cleans well, and I have been satisfied with it. If it were my only vacuum. I am not sure there would be any love lost.