If you put London Pass into the search (good grief it is a poor search engine, but it is what we have - if you are mobile find search under the three bars, if laptop or browser, search is the area in tint at the top of the page with the magnifying glass and says Search) area and you can find many previous threads on it.
I've never used one because I am local.
The general consensus is that they are expensive and you need to carefully do your homework. They include a large number of minor and very minor attractions which makes it look like a great deal, but the reality is that you can only do so much in the time you have. You'll never get to most of the included places.
It is also true that most of the top museums in London are free for entry so you don't need any pass for that.
They market the pass appealing to the desire that many visitors, especially Canadians and Americans, have to "skip the line". The truth is that most places have no line, and the 5 - I believe it is 5 - places which the London Pass actually gets you to the front don't include the worst lines.
You can buy tickets for the worst lines on line and that gets you to the front too. And at more places. And you get a discount.
Nobody skips the security lines at most places, free or with a pass or with a ticket.
Does the pass you are looking at have a transportation component? If you use a normal Oyster for transportation you can get any left over unused money at the end of your trip, and the deposit, back. With the Pass I believe that it in includes all 6 zones which you are unlikely to need - but you have to pay for.
Consider if you want an included hop-on-hop-off bus. Threads about them can also be found in search, or just scroll back a few pages - they are a frequent topic. Traffic in London and slowness of the loops mean that some people don't see them as the value others do.
It is easy to take a normal bus with an Oyster card, and get the great view from upstairs, as you link together places you want to go. The number 11, number 15, number 9 are all good local buses - there are lots more - for viewing London from up high.
Not asked in your question - but here as a bonus answer - is that there are many high vantage points in London now in addition to the Shard (way overpriced) and London Eye (also not cheap, in all the years I've lived near London I've done it once, just after it was built). Places like Tate Modern, One New Change, John Lewis Oxford Street roof event, and the Sky Garden are just some of the free places with great views.