OK brief ride report...
It's a moderately interesting country to cycle in.
Getting about
The roads are good, though there tends to be a network of small roads in each area with villages with a single major highway between areas. These can be new DC which are great as there's not much traffic on them so plenty of room, or SC which can be a bit hairy. There's always a hard shoulder but of poor quality making cycling on it very slow. Some of the mopeds on the main highways do less than 25 km/h so there's no issue cycling on the carriageway but you have to keep an eye out for overtaking lorries coming straight towards you and be ready to bail out. There are police/army checkpoints on many intersections but mostly disinterested.
Cycling
There was much suspicion of me bringing a bike in through customs, and even more on the way out. I saw no other cyclists on any road outside a built up area. Other than the usual odd old man in a village, there were quite a few lycra'd young people in the city centre on Sunday morning, but I suspect they were just going to cycle up and down the promenade for a couple of hours. So I was quite a novelty in every village I passed through.
Things to see
Most stuff is along the coast, apart from the grand mosque at Kairoan. The architecture is uninteresting on the whole, if there was once some French colonial influence it has all gone. There are a few places with little winding streets and white-painted old houses, but mostly it's either modern apartment blocks or run-down village houses. The ancient monuments like the Rabat in Monastir and the grand mosque are extensively "restored". There are virtually no other tourists in January so I was mostly the sole visitor to any of the sights, but they are pretty small and far between each one. The landscape is pretty flat with long straight roads through endless olive farms (Tunisia is 7th largest olive producing country) and salt lakes. There are some mountains further inland, but there are few roads and settlements anywhere but the foothills. The cities of course each have a Medina and within that a Souk, which is fascinating once but they are all virtually identical.
Food and accommodation
Along the coast there's obviously plenty of seafood. Ojja is like Shakshuka, eggs baked in tomato sauce and can be had veggie. Inland the street food is mostly grilled camel or goat. The locals eat pizza or wraps - "baguette Farsi" which is pizza dough stuffed with veg and meat or tuna, rolled up and cooked in a pizza oven, or "chapatti" which is thick round bread like a big arepa, sliced down the middle and filled with cheese and fried eggs. Everything has at least a jar's worth of harissa in it.
Alcohol is mostly not available, despite Tunisia being a wine-producing country, though in Monastir both beer and wine were served and the muslims were not holding back.
There are no hotels at all outside the major cities, and they vary from €10 for a normal three star hotel to €400 a night for European chain.
Overall
I had a good trip, but overall I'd give it 5 out of 10. It's safe and the people are friendly. The sights are small and a good half-day cycle between. The villages are near-identical and the cycling is either uninteresting or pretty scary. If you've never been to North Africa, go to Morocco.
Anything else?
Yes, it's totally filthy. There are plastic bottles, cans and broken glass across the whole countryside, blown plastic bags stuck on every cactus, and the same on the beaches. A couple of spots I had to stop and carry my bike as there was so much glass on the road. The dogs were not a problem, barky but no issues.