While there is much familiar about Castlevania: Order of Ecclesia, it is not content to exactly follow the established mold of its forebears.
It seems easy to fault franchises with fundamentally similar entries for being repetitive. Innovation is certainly important, and as many series have demonstrated (the Tony Hawk series is a notable example), modest annual updates can certainly begin to wear thin their welcome. On the other hand, Nintendo, for example, has clearly demonstrated an ability to develop extraordinarily similar yet extremely enjoyable games time and time again with their keystone franchises. Although they have taken some criticism for this similarity, and even as innovative strides have recently been made with titles like Super Mario Galaxy, it bears some thought as to just what it is about their particular approach that allows them to be successful in this way.
It can't be all in the core mechanics of play. Tony Hawk has always been mechanically sound, but that has not prevented its luster from fading. It is also difficult to argue that it's necessarily the amount of time between titles. Ratchet and Clank has had annual offerings for some time, all well regarded. In fact, the least critically successful, Ratchet: Deadlocked, was the one that attempted to somewhat alter the formula of the series. Perhaps nostalgia enters into the equation somewhere. But while Nintendo may be home to the most obvious examples of these kinds of franchises, it isn't the only one. For the past several years, Konami has released a number of well designed, fundamentally similar, and critically acclaimed titles in the Castlevania series.
Few would argue that the PlayStation title Castlevania: Symphony of the Night is a modern classic, and for many, it remains both a turning point for the series, and for 2d action adventure gaming in general. While no other Castelvania titles in the Symphony of the Night vein have appeared on home consoles (with the exception of the re-release of Symphony of the Night itself on the PlayStation Network and Xbox Live Arcade), the style has certainly found a home on Nintendo's portable consoles, with three critically acclaimed titles on the GBA and two on the DS. While all have been fundamentally similar to Symphony of the Night, itself clearly inspired by the exploration mechanics introduced by Metroid and Super Metroid (spawning the term "Metroidvania" among fans, as a way to characterize the style of play), they have all been quite enjoyable due to sharp presentation and exceptionally smart level design.
While there is much familiar, then, about Castlevania: Order of Ecclesia, the sixth game in the franchise since Symphony of the Night, it is not content to exactly follow the established mold of its forebears, and its touches of uniqueness are well-placed. Aria of Sorrow, the last Game Boy Advance Castelvania title, and Dawn of Sorrow, the first DS one, increased the roleplaying elements of the series in the form of souls collected from fallen enemies. Finding the rarer ones sometimes required leaving and re-entering the same room, defeating the same enemy over and over again, adding some of the addictive collection qualities of titles like Pokémon. This, however, was not the case with Portrait of Ruin, which had a much more basic purchasing system. Order of Ecclesia brings the roleplaying aspects back in the form of glyphs, and goes a step further by allowing them to be equipped in combination, vastly increasing the customization options available.
At this point, though, the portable Castlevania titles, enjoyable though they may be, seem unlikely to attract many new players. Even though Order of Ecclesia has key differences from its forebears, it still does represent a style of gaming that has been largely supplanted by more three-dimensional titles. This may not be a notion that is lost on Konami, as they have only released the "Metroidvania" games for portable consoles, with their relatively lower development costs. Another sign that Order of Ecclesia may be intended for longtime Castlevania fans is that it is noticably harder than any of the previous DS or GBA titles, particularly in the boss battles. With the increase in popularity of original downloadable titles from XBLA, PSN, and Wii Shop, it might be interesting for the next Castlevania title to be released in that format, if only for the opportunity to play it on a larger screen. Still, as long as they are being developed at all, there is little for fans to complain about.