When you're combining working with travelling, a coffee shop can seem like a good place to get some work done, but there are several disadvantages. I've included some workarounds where applicable!
1. Wonky wifi
Access to wifi can vary dramatically from country to country and cafe to cafe. Cafes generally fall into two categories: either the owner has set up a router for free wifi, or they've used a third-party company to set things up. In the former case, often the wifi is slow and unreliable. In the latter case, it's often very expensive compared to home broadband connections (here in New Zealand, US$5 for 50MB of data is normal). Tip: If you've got a smartphone, you can hover near the entrance to the cafe and do a "test run" before firing up your laptop!
2. Not-so-comfort zone
The sofas and coffee tables in most coffee shops don't encourage a good working posture. A good office chair will ensure you sit upright and support your back, as well as having the desk top at a good height. Using a laptop for extended periods in an awkward position could lead to RSI. Tip: scout around for the best chair and table. Take more frequent breaks than you would in a regular office chair.
3. The calorie kicker
As well as the possible health dangers of drinking too much caffeine, don't forget the amount of sugar in blended coffee drinks. A Starbucks grande caramel macchiato contains 270 calories and 10 grams of fat. Don't even ask about the Eggnog Latte. Tip: stick to espressos, or drink tea.
While a coffee shop may work fine for surfing the web or typing a document, what about when you want to make a phone call, scream loudly at your computer for misunderstanding you, or play some music? Tip: good headphones, and pop outside to answer calls.
5. Power cut
There are never enough power plugs to go around, so expect long cables straggled around the coffee shop, or taking it in turns. Tip: Make yourself popular by carrying a small plug splitter, allowing several people to share the same power outlet.
Even if the wifi's free, coffee in a coffee shop is 10 times more expensive than making it yourself. Be aware that you're really paying for real estate: particularly in busy cities, the staff may not like you hanging around all day using up space. Tip: be friendly to the baristas and tip (it's a lot cheaper than buying another drink).
So, what's the alternative?
The alternatives to coffee shops are varied, although all solutions have their advantages and disadvantages. If it's reasonably priced, your hostel or hotel may be a good place to work. Public libraries often provide free access. Or investigate local co-working spaces.
Having a smartphone with a 3G connection provides a backup allowing you to get internet access almost anywhere. The most important thing if you're relying on having Internet access is to have a few backup plans available!