To cut to the chase, Spiderman 3 was... part great, part awful. On the one hand, amazing cinematography and special effects, on the other hand a soulless script, misguided patriotism on the part of the director (this scene in particular reminded me of Raymond Chen's classic saying, "I bet somebody got a really nice bonus for that feature").
There is so much going for this movie that I couldn't help but attribute most of its shortcomings to a surprisingly shallow screenplay; my theory is that Sam Raimi's background as a B-Movie director ("in the trenches" is the term I'd use), while affording him impressive technical innovation and brilliant tongue-in-cheek humour, does not lend as well to his screenwriting abilities. The first two Spiderman movies were written by professional writers, and with Raimi's superb(not to mention distinctive) style of visual gloss the combination is very effective. For some reason the Raimi brothers took it upon themselves to write the script for the third movie, and it suffers accordingly.
Overt patriotism (which was much more subtle and agreeable in the first two movies) is very awkward for a superhero that is, in many ways, the antithesis of his contemporary who swears to uphold "truce, justice and the American way;" this reflects in the acting, and outlines how artificial those scenes were. The same goes for most love- or romance-related scenes which also felt forced and superficial. Tobey Maguire, who seemed in the first movie so appropriately docile and nerdy, on the second suitably vulnerable, now seems a little out of his element; in his defense, the over-the-top dialogue and violent mood-swings called for in the script would probably make any actor falter. A lot of the script just doesn't work.
Sandman is, and please remember that I have not actually read the comics, an utterly uninteresting character. It seems like a subplot, and one that doesn't make sense at that (it was never obvious to me why he fights against Spiderman); Thomas Haden Church plays, in this case, a very lethargic character that has - whether due to bad scripting or bad acting - very little depth. This would be a good opportunity to oppose a conundrum (minor spoiler ahead): at least once during the movie a fake news broadcast is shown, in which the anchorman provides commentary on the proceedings in real time. The anchorman provides the audience at home with the particular details of the combatants, and names them accordingly (Spiderman, Sandman, Venom). As my friend Yoav puts it, "who gets to decide these names anyhow?" (link in Hebrew)
On the plus side, James Franco actually seemed to learn to act, or maybe lack of any significant screen time in the first two movies never let his talent show. His dialogue is, ironically, quite sensible, and he carries it off very well indeed. A cameo appearance by the legendary chin is utterly hilarious, the music is great and the cinematography - as I previously alluded to - is simply fantastic. I'm not in the business, but I wouldn't at all be surprised to find out that Raimi has invented any number of new camera techniques in the course of filming Spiderman 3 alone. The special effects are brilliant and there is non-stop action - most of which is really good.
In conclusion, to reiterate the first sentence in this article: Spiderman 3 is not a bad movie, nor is it great (that title is reserved to the first movie in that particular series). I just wish Sam Raimi would stick to what he's (very) good at and leave the screenplay in the hands of people better suited to the task.
Lastly, it's worth noting that I saw this movie in Pathé Tuschinski in Amsterdam, which is undoubtedly the single most impressive cinema I've ever been to; it is a very large building, reportedly built in 1921 in the Art Deco style, and much more impressive on the inside than on the outside. Theater 1 is huge, spacious and comfortable, with an astounding number of chairs and two (!) levels of balconies. Audio and video quality was excellent - possibly the best I've ever experienced, and the lobby alone is worth the price of admission which, excluding discounts or sales, is €9-10 - quite pricey.