As a language it use an M-expression-like syntax. See http://en.wikipedia.org/wiki/M-expression
So your point about symbolic versus numeric flavor might have been correct prior to version 6, but it is no longer true (Mathematica 10 will be released later this year). In fact, they now use many of the same libraries for pure numeric work.
Numeric (as well as hybrid numeric+symbolic) computation is possible in Mathematica. In MATLAB, symbolic math requires a clunky add-on that is far from competitive with what Mathematica can do.
I work at Wolfram.
If memory serves, 5.2 was the then-current version. It's an amazing piece of software.
Solve[{x + y + z == 3, y + x == 4, z + y == 7}, {x, y, z}]
gives: {{x -> -4, y -> 8, z -> -1}}
Refactoring our documentation a bit for M10 will help, the predictive interface in M9 helps, and there are some cool "code hint" ideas that are coming in M10 that will hopefully make it easier to keep learning.
We'll also soon be launching a community site to make it easy to discuss functionality, seek answers, and share code. For now, http://mathematica.stackexchange.com is a good resource.
We're also working on getting some materials about the Wolfram Language that should make it easier for people with existing programming experience to grok what is unique and different about WL, and how they might go about learning it.
Probably the best resource remains the existing Mathematica documentation. It is vast -- containing for example more than 100,000 evaluatable code snippets that demonstrate each function being used in multiple ways.
It is available online (http://reference.wolfram.com/mathematica/guide/Mathematica.h...) as well as in-product (double-click function you want to know about, then press F1 or Cmd+Shift+F). Following hyperlinks from familiar territory can get you a long way.
It's quite easy to get lost in it, of course, so here's a short list of "bread and butter" functions that I think every WL programmer should know really well: https://gist.github.com/taliesinb/5848321
Lastly, here is an eclectic mix of guides that might serve as good 'anchors' for some documentation spelunking:
http://reference.wolfram.com/mathematica/guide/LanguageOverv...
http://reference.wolfram.com/mathematica/guide/RulesAndPatte...
http://reference.wolfram.com/mathematica/guide/Patterns.html
http://reference.wolfram.com/mathematica/guide/StringPattern...
http://reference.wolfram.com/mathematica/tutorial/BlocksAndL...
http://reference.wolfram.com/mathematica/tutorial/LevelsInEx...
http://reference.wolfram.com/mathematica/tutorial/ApplyingFu...
http://reference.wolfram.com/mathematica/tutorial/Manipulati...
http://reference.wolfram.com/mathematica/tutorial/Introducti...
http://reference.wolfram.com/mathematica/guide/SymbolicGraph...
http://reference.wolfram.com/mathematica/Compile/tutorial/Ov...
http://reference.wolfram.com/mathematica/guide/GraphsAndNetw...
http://reference.wolfram.com/mathematica/guide/MatricesAndLi...
This is compounded with the fact that Mathematica's main advantage is in its combinatorial possibilities (just like other more popular programming languages), and not in any specific application.
Think of it as marketing Lego blocks as a business-to-business product.
So your university / company has a licence, and you are naturally sceptical about something that has a definitely weird syntax, they need to tell you "this can help you somehow" and "it's actually better this way".
And if your employee asks you for a licence, and you are naturally sceptical, they need to tell you "this is actually useful in tons of other problems".
As with many applications or languages (or, in this case, both), being exposed to it at the right time creates a client for life. Those lifers become evangelists in the same way lispniks do (and watch out for those of us who are both), requesting that employers license the software.
If you are between, say, 35 and 45, went to a "decent" university (i.e., one Wolfram and/or NeXT targeted), and have an applied math background of any sort (CS, physics, engineering, etc.), you were very likely exposed to Mathematica. It's just a few steps from there to having a prof use it in a lab or using it because an employer had made a previous investment in development.
At that point, much as with C, or Java, or CLISP, or whatever, it becomes a fallback computational tool. SAS acquires many of its licensees in a very similar way.
So as a non-Mathematica user, it certainly appears to be a very effective technology, and in the right hands and right domain, it seems like it could pay for itself very, very quickly.