Which phone was it? Sony has products in the low, mid and high price range and the cheaper phones naturally are weaker than an iPhone. If you compare the flagship models of the two brands the Xperia is at least on the same level of power as the iPhone.
And as an anecdote: I had an iPhone a few years ago and hated it most of the time (and I say this while using a three year old phone that cost me 200€ at the time)