I use the local branch of Boot's and don't have any complaints. No pressure at all to buy new spectacles from them, in fact, quite the opposite; the optician noted a slight change in vision, but said I'd be unlikely to notice any difference if I bought a new pair and advised me not to bother! He did ask if I'd considered contact lenses or corrective laser treatment and explained the costs, pros and cons and procedures involved. Not for me, but it's good to be given the option.
The only minor niggle is that it seems to take a long time for the results to arrive at my GP's surgery, but whether that's Boot's at fault or the NHS, I really don't know.