Hi Tubegroover - the main thing about the 5th symphony is what I alluded to in my previous post. Instead of a longer melody, the "theme" that is developed is simply that four-note motif at the opening of the work. This was the radical aspect of it, if you will, though interestingly there is nothing "Romantic" about that part of it - in fact, it is a concentration of a very Classical procedure. It also has the expanded codas, and the interesting transition between the scherzo and final movement. But despite these things, it is a very Classical work, in form. A better choice for your argument would have been the Eroica symphony, with it's vague association with Napoleon, and the "heroic" concept, though again, very Classical in form. Or the Pastoral symphony. But even with those two examples, Beethoven was very insistent that there was not real "program," as there would be in Berlioz Symphony Fantastique, a much more "Romantic" work, or the tone poems of Liszt. These are the sorts of steps Beethoven pointedly refused to take into the Romantic era.
In style, yes he is quite a bit different from Mozart and Haydn, though Mozart also foreshadowed the Romantic era in many ways in his operas, especially in Don Giovanni and The Magic Flute. In his symphonies, Beethoven used a wider range of dynamics and a wider variety of articulations, and took full advantage of new innovations in the instruments themselves, deliberately pushing these boundaries, and in this way he is closer to the Romantic era in spirit. And of course there is the innovation of the chorus and soloists brought into the realm of the symphony. But that said, he is essentially a Classical composer - he did not experiment in new forms, as the early Romantics did. In fact, a great many early Romantic composers decided Beethoven had done all that could be done with what they considered an essentially Classical form, the symphony, and avoided it altogether, Wagner being the most famous case in point. Others disagreed, particularly Brahms, who is of course considered a very conservative composer because he stuck to the Classical forms.
Sorry for the rambling post, need to get to bed.