That's how most lenses are, you can't expect DSLR quality from a $150 set of lenses for a phone. DSLR's can give you virtually no distortion, or issues at a steep price of course. I'm happy with the lense kit especially after eBay gave me $100 off my order due to an issue (they just told me after the fact without me even calling or asking for anything), so I effectively paid $20 for it and $27 for overnight shipping from South Korea. To me the ~$50 I paid even the original $130 is still well worth it.
$100 off? Dang you got lucky. Lol. I'm finding it hard to justify spending close to $200 on this accessory. Meh. I guess I'll need to wait for a year or so before it comes down in price.