I don't know about 7.1, but 7.0.x is really slow. Also a battery killer.
I'll try 7.1 when it gets final, but I'm pretty shure I'll roll back to 6.1. I really do not encourage people (owners of iP4 mostly, although 4S got a considerable performance hit too) who don't have their blobs (4, only) saved to 'upgrade' to iOS 7.
I've also experienced frequent crashes of Settings app.
Just for the record: GTA:SA is playable on iP4 iOS v6.1, whereas on v7.0.x is like watching a slideshow - and a poorly executed one, w/o transitions. 🙂