I think you can take the lack of screenshots as a hint of what is to come.
I will walk you through the process:
plugin installed - settings are clear and simple with number of seats available, opening times, days of the week and info on the restaurant incl. name, address, country, phone, email, URL.
Automatically a page called "Reservation" is generated. When you go to that page however, the entire from is placed outside of the page (yes, I tried that too with the default theme - see screenshot).
The plugin does not look at all at the timezone of the general WordPress settings and instead chooses a time in I think UTC-1, maybe UTC-2. Looking through the code it seems that the earliest reservation time is set to 3 hours after the current time; a good thing if it was comparing the actual time with the general settings. In my timezone it's possible to reserve a table 6 hours ago...
For the rest the form works nicely, after selecting the time and for how many people you get to step 2 which let's you confirm the time and gives you 4 other possibilities.
During step 3 you need to fill in your details such as name, phone, email and any comments you might have.
after clicking "make reservation" this message shows:
You reservation has been accepted. You will receive confirmation by email.
Note to plugin developers: run a spellcheck.
Now we're getting to the worst and most shocking part of it all.
I received my confirmation email (copied straight from the email):
Your reservation has been confirmed. If you cannot be present, you can cancel the reservation any time by using the following link:
Reservation #: 594
Place: Restaurant, restaurant address, city
Time: 16:30 - 19:30
Your contact details:
Reservation Diary Team
reservationdiary.eu ??? WTF
And WTF is that link doing at the top???
Going there it turns out that they have copied all details, of the restaurant and of the customers.
You can just wait for all the spam that you are going to receive!
THIS PLUGIN IS A TOTAL SCAM!!!