Diffidently an improvement in my opinion. Although I would imagine some of those who manage shared hosting, will need to take into account some of the changes in features. Will be some time before I suspect I'll see this imputed in that kind of hosting environment.
But diffidently an improvement for those of us who use vps / dedicated.
had same problem but just heads up latest trunk release of APC has fixed PHP 5.4 compatibility and I tested with nginx v1.1.18 and PHP-FPM 5.4.0 with APC 3.1.10 trunk release and it works but still other php extensions don't i.e. FFMPEG and Suhosin.
Haven't checked it Xcache works with PHP 5.4.0. I know Memcache php extension v2.2.5 trunk release has fixed PHP 5.4 compatibility but Memcache >v3.0.6+ don't see it yet.