I just watched the new film Beowulf (in 3D). The film was quite a good one - creating an easy means to access the much more difficult to read translated book. However, to people who haven't read the book, this film is not (surprise, surprise) a faithful translation of the original Old English "classic" epic poem. (For example, in the book, Grendel's mother wasn't a gold-tinged Angelina Jolie look-alike with - strangely - high heels and tail.)
The major drawback (in my opinion) was the diminution of the role of the hero in epic poetry and ancient societies. Having watched Troy in recent days, the parallels between the heroic characters Achilles and Beowulf become clear. Having recently watched Troy has also shown me how apparently shallow the hero theme (fighting for glory and immortality) was explored in Beowulf (yes, they talk about being sung for eternity, but it wasn't pressed to the same extent as in Troy). I feel this theme was altered slightly to try and show Beowulf as a human being with his own failings culminating in a desire to (in the last act) redeem himself by righting the wrongs he helped create as a young man. True, in the original Beowulf, the character (to my recollection) wasn't really trying to redeem himself of any wrong, but ended trying to die a glorious death in combat. The women in his life were mentioned only secondarily in the text (again, if I recall correctly). Although this type of character is alien to the modern viewer, I don't feel that the way to mainstream the film is to alter (some might say "explore") the character, but be explicit that it is set in a context of heroism and (like in Troy) possibly show the dichotomy of the heroic and the politic.
If you want to watch an action film, then this isn't the film for you. The action sequences (although bloody and hair-raising) are only quick blasts of action spritzed sparingly in the rest of the film.
No, the plot changes and plot twists that aren't in the original text (at least in the copy I recall reading) weren't really a bad thing, in my opinion. In fact, they possibly lent more continuity to the storyline. Of course, how the director decided to show this new script did have a negative outcome on the role of the hero (see above), however, since I feel that the plot changes did not force the diminution mentioned above, I'm not going to say the changes were all bad.
The film is very enjoyable in 3D, and if it wasn't for watching it in that format, I would say that the whole thing might not really be worth it... The fight scenes are all well choreographed, and when Beowulf strips down completely, the animators took great pains to make sure his (erm) penis wasn't showing. (Still, a little beefcake for those interested in that sort of thing.) However, for being a "bear of a man," Beowulf wasn't really rendered as being really "bear-like" (not hirsute or brawny enough to really be called "bear").
The cinematography was well drawn and directed. The characters were still somewhat plasticky in their look - many of them were (while being well rendered) were not realistic looking (interestingly, Beowulf was significantly more real-looking than any other character in the film). However, the inorganic items (the pebble beach, the flames, the castles, the cliffs, etc) were really great.
One last gripe and I'll be done: the thing is a period piece - taking place sometime after the fall of Rome, but not too much - and as such, one would like to see some realism along that vein, but in some interesting respects Beowulf falls down on this. Hrothgar's castle keep (while never entered in the film) is a major tower built along a scale that would never be seen until the Crusades. At the end of the film, the keep has expanded to massive tower proportions, and the stoutness of the castle walls would have made the castle builders of the 16th century envious. Additionally, Beowulf is seen wearing what looks to be plate armor. Where did he get it? That technology wasn't going to be around for another few centuries. (One might argue that it was colored leather, but it seemed to me to be rather shiny for leather.)
See the film (if you can see it, in 3D). It makes a good part of a collection alongside 300 and Troy.