is the London Eye River Cruise worth it?

worth what?

It is just one of many different options for a boat ride on the Thames. If you plan on taking a boat trip anyway, it is as good as many. But that depends on what you want to see from the boat. This one travels R-T Eye Pier > Tower Bridge > Eye Pier.

we were wondering if it's worth the time and money. We haven't really planned any boat trip so should we even consider it? We only have 2 full days in London as it is.

IMO w/ just 2 days - skip it (and most any river trip). Unless you've been to London before - 2 days is barely time to see 3 or 4 major sites. (Is that 2 FULL days or 2 days including your arrival and/or departure days)

The boat ride is about 45 mins but all in all would essentially eat up an hour.

We enjoyed the Thames cruise last time we were in London, our 8+ trip to the city. But I agree with janisj (who always has the best advice!), with your brief visit, do something else in London and save the boat ride for another visit.

I took a river cruise when I was in London last June, and quite enjoyed it - I do love boat rides, though, so I suppose it depends on what you like. It was a good way to see a lot of landmarks from a different perspective. I sat on the upper deck, I doubt it would be as enjoyable from inside. I'd only do it if the weather was decent, so you could be outside. The commentator on our boat was very informative and funny. If you plan to visit both the Tower of London and ride the London Eye, this could be a good way to travel between them. You could go in either direction, depending on which you wanted to do first.