The changes are:
- The Google site-search facility is back, and the Google search box under the right hand side of the header has returned after an absence.
- HTML links on the site are no longer underlined by default, some such as manually inserted links in posts are specifically underline. If there is any particular example of a place where a link has become too obscure, let me know and I will sort out a fix.
- There are now highly visible buttons at the top and bottom of forum and topic pages for subscribing to (notifications of) new posts in those forums and topics. You can control whether you generally get email notifications for a category of site notifications by using the settings link from the notifications drop-down at the top of the page.
- There have been minor updates to the posts bookmark feature.
- There were (a few weeks ago) some changes to the appearance of the site header and associated buttons. This was particularly intended to improve usability of phones with small screens.