As a first time customer you don't get a decent idea whether the product is up to expectations until delivery / install. So when the fitters arrived and were so efficient and the attention to detail excellent spot on I got the idea that all was good.
In a nut shell:
1 Product - excellent
2 Cost - acceptable
3 Lead time - no problem
4 Fitters - excellent*.
* All rubbish and packing bagged up and taken away - very good. Windows left polished and stickers removed - very good.

I’m surprised at the 1* reviews as my experience was really good from their Poole office. Would have been 5* but lost one for the long lead time and 2 surveys needed beforehand.
The fitting team of 6 were really efficient in removing the large single gazed units from a 4th floor 1960’s building and replacing with large sliding patio doors to the balcony and floor to ceiling unit in the dining area to mimic the original design of the window.
They both look great, giving an almost 30’ wall of glass looking seaward. A really professional job.

I hardly write bad reviews as I believe that there is always a good way to compromise and adjust defects through good customer service and prompt company supports. we have been dealing with ODC since 2021 and I waited a long time before deciding to write, but the level of frustration and disorganization has been so high that I'd rather spare anyone else a very long and bad experience.
We decided to go with ODC windows for our house refurbishment as they offered a very competitive price. However, the quality of the products is also quite basic. They seem extremely efficient in getting paid in advance.
Worst of all has been our experience with the installation service ODC provided on our project.
The first team of installers included an underage apprentice who was left in charge of unloading the glass without supervision.
Basic Health and Safety measures were not in place when the breakage of the 5 large panes of glass out of 7 at the beginning of the day could have seriously hurt someone.
The team then installed just 2 of the 7 window frames before deciding to leave the site for the day around 1pm.
We found unacceptable that they did not even attempt to finish the job or compensate for the damaging start, despite all the time available, but also did not bother to clean up after themselves, leaving all the fragments of the broken glass spread across the floor for us to tidy up.
The installation date took months of preparation to set up, both from ODC side and from our contractor's team committed to preparing everything for ODC arrival.
On the second day (this rather incompetent) ODC installation team progressed the job, without completing, leaving the windows unsealed from rainwater and December weather.
Two of the windows were wrongly installed and some bits were missing, so we complained again and the same team came back to try to rectify the issue unsuccessfully.
Many emails, telephone calls and complaints and two further visits later (total of 7 so far), two more competent teams (bless them) managed to take out and re-install in a better way.
We still have outstanding issues of bad installation due to the first incompetent team, that we have been trying to rectify in the last 12 months without success.
The response is extremely slow via emails and telephone calls and in the past two years we have spoken every time to a different person in charge of customers support.
Some people, like their operation director (bless him) and their surveyors, seem to be very competent and proactive, but the company in general seems to be a bit all over the place with people coming and going and not efficient management of the projects.
Following our frustrating experience and the issues we have been trying to resolve for the past year, I would not recommend this company for windows and doors

ODC Glass is incompetent at best and their glass is extremely poor quality. I have spent a YEAR going back and forth with the company trying to sort significant issues as every window in my whole apartment was significantly scratched when I moved in (despite the windows all being brand new), amongst other issues. It took months for ODC to replace the windows and even then the majority of the replacement windows contained defects within the glass itself, which is down to the poor quality of ODC's windows. I have had eight visits (and counting) from people from ODC and each time they were without the right tools, materials or correct sized glass to fully address the issues and there are still a number of outstanding problems they are yet to sort. My case had been referred to one of the company Directors and even then they have been continually incompetent and incapable of sorting these issues. I don't usually like to write a bad review, but I am extremely frustrated with having to change my work plans on a continual basis to have them visit to then be told they couldn't sort the issues that they said they could. If you are considering going with this company, simply save yourself the stress and time - don't do it.