Our aborted first attempt at buying was a house for sale through purple bricks and it was a nightmare. Dealing direct with awkward vendors who tried every trick in the book to wring more money out of us wasn't fun. The guy was constantly on the phone to me near the end, making threats to put it back on the market. Just had enough of their shenanigans.
I'd avoid any house on the market with purple bricks in the future.
The one we actually bought was through Firmin and they were fine to deal with. We sold through Newton Fallowell and they were fine too.
Our buyer and solicitors involved, another story unfortunately....
It's really about the other party in the transaction. If your seller is a nobhead then no agent is going to make it a pleasant experience.
I'm nearly at the end of a purchase through Purplebricks, and it's been excellent. Easy to arrange viewings, easy to negotiate an offer and the contents listing. No complaints at all.
I'd say about 50% of the high street estate agents I used never bothered returning calls or arranging viewings when requested. Booking viewings online is so much easier.