They are quite expensive although the WiFi board has Li-Po charging circuit.
I probably will not be using them due to the price: €27.90 + tax for the WiFi version.
The included Li-Po charging circuit would save space but of no use if you do not use that option. Also I find the pre soldered headers are a pain in a lot of cases and I used to find my self having to mess about un soldering them when using an Uno.
At least it looks like they will fit on a bread/stripboard unlike the Uno.