I started playing this game a few months ago and just completed all of it.  Super Mario Bros. Deluxe features not only the 1985 NES original levels, but also the Japanese version levels that North American players couldn't have before.  At that particular time, the only other way that anyone could access those levels was to play Super Mario All Stars for the Super NES/Nintendo Wii.  However, the NES Japanese levels were finally included on this 1999 Game Boy Color port/remake.  (For those of you history buffs, the Japanese version of Super Mario Bros. was actually named Super Mario Bros. 2.  The North American version of SMB2 was completely different and released in 1988 with Wart as the main archvillain, not Bowser.)