Deutsche Bank analyst Sherri Scribner believes expectations for iPhone sales this year are optimistic based on the tenth anniversary launch and the belief that the installed base is "ripe for an upgrade."

The analyst says she's more cautious, citing slowing global smartphone growth, elongating refresh cycles and the expected high price of new models. The current valuation of Apple (AAPL) shares is fair following the recent rally, Scribner tells investors in a research note.

She keeps a Hold rating on Apple, but upped her price target for the stock to $125 from $115 to reflect higher market multiples. Apple closed Friday up 38c to $135.72.