People who think Victory Rush is overpowered are probably those who have not played many other classes other than Warriors.
After leveling both a Rogue and Druid recently, I can say that Victory Rush is in no way overpowered.
Mutilate Rogues have 100% uptime Recuperate, which is 2% health every 3 seconds, Combat Rogues have 4% health every 3 seconds from Recuperate but don't get it refreshed for free like Mutilate Rogues.
Cat Druids get 4% maximum health proc heals on every Crit from Leader of the Pack with ~30+% crit rates in addition to 100% chance to proc free instant Healing Touches (which is around ~60-70% of their health pool) every 5 CP finisher (less for less CP)--both of which the mechanics are available mid-fight and not afterward. They also gain mana from Leader of the Pack which can be used on instant HoTs.
Victory Rush is quite nice, but no more powerful and probably weaker than many other self-healing mechanics out there. Most classes got things that reduce downtime between pulls while soloing, and Victory Rush is that for Warriors.
Cat Druids, for instance, can solo basically any elite or 2-3 man quest with 5 CP Healing Touch + Rejuv combos between DoT refreshes (Rake -> Mangle -> Mangle -> Rip -> HT -> Rejuv -> Mangle -> Rake -> Mange -> Rip -> HT -> Rejuv -> etc...) which Warriors have a hard time doing unless they go Prot and use cooldowns.