I’ve used the Fishponds and Salisbury branches for tyres, exhausts and MOTs only.
They pointed out issues I knew (blowing mid-section, broken manifold mount, missing locating bits on the alloys) but never upsold me. The last time I used them was for an MOT, and despite having a full advisory section, they passed my car. One advisory was that it had a nail in a tyre!
Friendly and fast has been my experience of kwikfit.