There is quite a lot of information on Cosentino's website about this surface. https://www.cosentino.com/en-gb/silestone/ It may be too soon to get a good proportion of reviews, positive and negative. I would speak to a few high end kitchen design companies and find out whether they are specifying it and what the feedback is like. If there are problems then they would most likely have to deal with them as the worksurface would have been sourced and fitted through them, not independently. Order quite a few samples in the finish you like and then do stain tests yourself with lemon juice, red wine, etc. I would also try to get a slightly larger piece and do edge chipping tests. I agree that the warranty is unlikely to cover accidental chipping on edge. Your decision entirely.

@Oraanj interior design- thanks for your suggestions. We were tilted towards first option of just going with sill after the builder told us about access but then we told the worktop company, they said it would need a re-template and we need to pay for it and plus they do not have a template date soon which is adding to the cost and delaying the works.

Hopefully, silicon hasn't been used in the joints, it should be a 2 part adhesive which is coloured, the joint looks a pretty even gap and is a lot better than many i've seen, also the worktop is polished and the jointing compond is a matt finish so that makes it stand out a bit as well. One thing though is that with a veined worktop like you have, the joint will always be more pronounced due to the change in pattern direction and there's nothing you can do about that. Silicon though was probably used where the upstand sits on the worktop.

I think this is normal for quartz and it’s probably only noticeable where the light is shining in from the door. I noticed splodges and cup ring marks on an area on my Silestone quartz island where the light from window shines on it. Over time these marks have disappeared but new ones have appeared. I am careful about using coasters now when I set down a mug of tea or anything cold from fridge, which I didn’t think I’d have to do as everyones says how low maintenance quartz is. I am aware though I have a hawk eye and notice every detail! If you contact the installers they might come out and buff it for you with specialist equipment - they did this when mine was installed as I could see marks which they were able to buff out.