I switched to the beta 2 days ago when the button appeared & was very hesitant (considering the previous swap of profile pages came with a lot of issues & things not working), but i have to admit so far everything is working fine, like the show of "downloaded/update available" on mods i downloaded, new/updated tabs etc.., everything else seems to work fine too on mod pages, the only issues i have with the new "theme" is it's a bit big... previous classic was nice flat & smaller (not too small you couldn't see or read stuff, but small enough that it didn't make you feel like 1 thing is taking the whole screen over which this new theme feels like), i hope we get an option for a theme in the future or at least a default & smaller size to pick from.
as for you, what you mean you can't view mods images without navigating to the mods page? if you mean the thumbnail it works fine, if you mean screenshots posted by author & other users for a specific mod then as far as i know you always had to go to the said mods page to view those...