Umm people need to learn the meaning of "underrated", too many use the word without really knowing what the meaning is. Many people call games "underrated" but they just mean it doesn't have that many sales.

Except that's not entirely incorrect.  Many people place the perceived value of a game also based on how many copies were sold.  Someone would consider a very well received, but low selling, product as "underrated" because people in general haven't accepted it as something they should get.  The "underrated" part is also relative to its potential demographic.

I disagree, people on this site seem to equate underrated to critics scores and that is not the be all end all of the definition of the word notice the "or" in the definition:

to rate or evaluate too low; underestimate

One could say that Nintendo has underrated the series by not producing enough of the games.  That could be because the market has underrated the series thus the low sales even though the critics have not underrated it in their reviews.

It, as so many things in life, is dependant upon perspective to provide context.

MDMAlliance gets it, so does sc94597

Critically? No. In terms of attention from Nintendo? Yes. In terms of attention from gamers? Yes.

I agree. This has to play into it. There are many people that love 2D. But many that love FPS. Which ever you pick, you lose one camp. Plus, the large gaps do cause problems. I gave up on Donkey Kong, since 64. And I know Tropical is a good game. But I ignore the series thanks to the bongo games. I got use to not looking at DK anymore.

I don't believe the Metroid series to be underrated. I do consider it to be underperforming, but such is the case in entertainment, whether it be film, music, or games with amazing products. Some of the most well regarded movies of all time did terrible in the box office (I'm looking at you Fight Club), yet their terrible counterparts (*cough* Titanic *cough*) have sold enough to fund small counries for 50 years. What's interesting is the way that many people around here will use high sales to establish a series' worth, when more often than not it simply means the product entered mainstream success, which doesn't always determines actual quality.

Kudos to the OP for enjoying the series and caring enough to sing its praises in a thread. It is well worth it as the countless number of Metroidvanias that keep popping up everywhere evidence. Speaking of which, if any of yopu 2D Metroid fans out there have not played Guacamelee, get on it right now! This is the closest thing I have probably played to a Super Metroid successor.

They don't overlap? Perspective hasn't really changed the Metroid franchise that much to be honest. Both Super Metroid and Metroid Prime have the same core gameplay and strengths. It is very much similar to 2D Zelda -> 3D Zelda. I think the period of releases is the more pressing matter. 

I agree, critically acclaimed but sales are much less than it deserves.

On top of that though I also think Metroid is underrated by those who haven't played it yet. I realise the same could be said of any great game but I think it's particularly the case with Metroid because it is particularly hard to get across precisely why it is SO good and SO worth playing.

difference is the Metroid series as a number of great installments - Metroid, Metroid Prime, Super Metroid, the GBA installments, etc. it has a lot of very high quality titles unlike Starfox (Starfox 64 being the only real stellar one in my opinion)

I agree with some posts, the series is obviously not 'underrated' (its very highly acclaimed), but possibly its not fully appreciated by Nintendo or by some fans (based on marketing and sales)