I had a Worcester Bosch boiler fitted 3 years ago in place of my 35 year old Gas boiler. Cant fault it. boiling hot water within seconds. Only had one call out to replace a divert valve that was pumping water in to the rads when it shouldnt have been. Their service plan is also good value at around £13 a month. Engineer came within 48 hours
Had one fitted only two months ago, so not really in a position to give feedback, good or bad. However, I have noticed that it uses considerably less gas than my old one (which was 17 years old). I got a deal which gave me a seven year guarantee.
Worcester have long been a good name in boilers .. Their 'Danesmore' oil boilers are absolutely everywhere .. and are big old reliable chuggers.
Worcester Bosch are much more up to date and technically much more advanced. They are built well though .. with common pump and motor parts (non-proprietory) so spares are available. The terminal noise is reasonably quiet .. if a bit weird.
Try to buy a boiler that is made by them .. not a cheaper one bought in and rebadged.
If you are having one fitted .. keep the condensate drain pipe inside/sub-surface.