I saw very little of Germany (just passed through, basically), so I can't say much about it. Germany has several large forests, which in general I consider A Good Thing. What scenery I did see was very pretty, but not wildly spectacular.
I saw very little in Germany, but I can say this: everywhere I went in Greece and Turkey, there were little signs that said, basically, "this is a copy; the original is in the (British or Berlin) Museum." I've seen the British museum, and it's incredible, so if the Berlin museum is anything like it, it must be incredible, too.
I don't really know. It was warm when I was there, but not hot.
Germany is relatively expensive, but not totally outrageous. Train travel in Germany is outrageously expensive. The only way to travel cheaply on the trains in Germany is to go on the weekend "long trains" (I don't recall their official name), which take absolutely FOREVER to get to their destination and require changing trains approximately 3,402,673 times. I took one on my birthday from Halle to Amsterdam, and it took from 6am to 10pm. I've definitely had better birthdays.
German food is tasty, but very greasy. Sausages and cheese are mainstays of the German diet. Fresh fruits and vegetables are widely available, but often expensive. If you've ever wondered just how many different types of sausage exist in the world, you can find out by going to Germany.
Germans are weird. They're not unfriendly, but they're not particularly friendly, either. They're not particularly helpful, but they're not rude, either. Two things which, though not all that bad, tend to annoy me about the Germans: 1) They often act as if they were experts about EVERYTHING, even things they know absolutely nothing about, and 2) they are VERY quick to point out that YOU made a MISTAKE (precision is a virtue in German culture, which makes a mistake almost like a sin), and when they point it out, it may seem like the most grievous error you possibly could have committed, even if it's just that you took a wrong turn. Many Germans speak English, but refuse to do so, because they're too afraid that they will make a mistake.
Many of the people I met in Germany were White, Middle-Class Germans who desperately wanted to be Black, Ghetto-Class Americans. They called their friends their "homeys" and thought themselves to be very streetwise, as if they had grown up in Compton or the Bronx. (This false sense of street wisdom may have something to do with why they get killed when they go to America.)
In general, I found the Germans to be somewhat anti-social, but I met a few whom I really enjoyed. I cycled with a German fellow (Hi, Dirk!) for three or four days in Greece, and we laughed so much that I thought we were going to cycle right off the side of the mountain on occasion; he gave me his address in Neu-Ulm, and though I don't know if I'll ever get a chance, I'd love to go visit him, and would be thrilled if he came to visit me in America. I have had German tourists (in a camper van, as they often are) offer me hot tea while I was camping, and a couple German girls in Italy gave me a ride into town from the youth hostel in Siena, and I ended up touring around the city with them. So, I don't have anything against the Germans, they just seem a little... well, weird.
I didn't spend much time in Germany (and I was staying with a friend-of-a-friend), so I can't really say, but I would guess that Germans would be quite clean. I base this idea solely on their propensity for precision, however, not on any experience. The countryside is generally fairly clean, as were the parts of the cities that I saw (except for all the construction that was going on, of course).
One thing the Germans do NOT have is much respect for authority or laws. Graffitti is an art form, and is so rampant that the government has set up places called the "walls of fame" where graffitti artists can show off their work. (Some of them are actually quite good, I must admit, though they almost all have the very same style.)
Most of what I saw of Germany was fairly flat and straight, but it isn't all that way. I traveled mostly by train in Germany, so my experience is quite limited.
Though I didn't cycle in Germany (I basically just passed through, staying a couple weeks in Halle with a friend-of-a-friend), it looked like a great place to cycle. Of any people on earth, the Germans are probably the best cycle tourists. They make absolutely the best panniers (in my opinion, absolutely nothing on the market compares to Ortlieb panniers) and if you can read German, you can get cycle-touring guidebooks for just about anywhere in the world. I hear that there are cycle paths through the Black Forest, as well as many other places around Germany. Just don't try to cycle on the Autobahn. ;-)