The free seat reservations are not even unlimited. You only get a few 'credits' to use, and after that, you have to pay the regular reservation fee like everyone else.
The credits are for "high demand" services (Eurostar, TGVs when beyond the cheaper fee tier and all international services, some sleeper services in seats only). Services that don't require credits don't have a limit on the reservations you can make (well, except the fair use policy).
I still believe it's pretty poor value for most people. For UK travellers who will need to endure a journey through the Channel Tunnel each way in most cases, it's probably not
that bad given Eurostar's normal reservation fees. Even more so if you wanted to travel around/through Germany with DB's reservation costs too.
Interrail said:
12.1.1. The Credits package for a Global Plus Pass consists of the following:
- Twenty-one (21) Type A Credits which can be used to book Type A Seat Reservations via our Website. Please contact our Customer Service team to see how many Type A Credits you have remaining.
- Three (3) Type B Credits which can be used to book a Type B Seat Reservation via our Website. The total number of Credits required to book a Type B Seat Reservation varies and depends on the service concerned and will be presented to you before finalising your booking. You can see how many Type B Credits you have left when logged in to your Account.
The total value of the Type A Credits is fixed at one-third of the Credits package, divided by the maximum number of Type A Seat Reservations that you may book. The total value of a Type B Credit is fixed at two-thirds of the Credits package, divided by the maximum number of Type B Seat Reservations/Benefits that you may book.
From
https://plus.interrail.eu/en/pass-purchase-conditions
I think the fact the credit count is the same for the 5 and 7 day passes is a bit odd, personally. But I also think not that many people will be taking more than 3 services where they want "free" reservations per day. Or if they are, they won't be doing that for the whole trip.
Yes, it's not clear whether TGV in France or the France-Italy TGV, or the France-Spain services are "free" to reserve or not.
It's quite clear, in fact ...if you find the right page!
Discover the new Global Plus Pass, offering you all the benefits of our standard Pass without the hassle of seat reservation fees.
plus.interrail.eu
I've trimmed the table to only those which cost credits, and included it below
| Where can I make seat reservations with the Global Plus Pass? | Carriers that can be booked with the Global Plus Pass | How many credits will a seat reservation require? |
| International | Eurostar | 1 credit |
| ÖBB Nightjet (seats only, sleeping accommodations cannot be booked) | 0 or 1 credit, depending on demand |
| European Sleeper (seats only, sleeping accommodations cannot be booked) | 0 or 1 credit, depending on demand |
| France | SNCF | 0 or 1 credit, depending on demand |
| SNCF International | 1 credit for most trains (1st class seat reservations from France to Italy require 2 credits) |