IME the one in Hemel Hempstead is much easier to navigate and I think that's because it's got a larger and 'solid' centre which provides a visual anchor.
For me the issue with the one in Swindon is that you can see right across it with only the signs and road markings to help you understand where you should be
For me the issue with the one in Swindon is that you can see right across it with only the signs and road markings to help you understand where you should be