<p>When I started writing database queries I didn't know the JOIN keyword yet and naturally I just extended what I already knew and wrote queries like this:</p>
<pre><code>SELECT a.someRow, b.someRow 
FROM tableA AS a, tableB AS b 
WHERE a.ID=b.ID AND b.ID= $someVar
</code></pre>
<p>Now that I know that this is the same as an INNER JOIN I find all these queries in my code and ask myself if I should rewrite them. Is there something smelly about them or are they just fine?</p>
<hr />
<p><strong>My answer summary</strong>: There is nothing wrong with this query BUT using the keywords will most probably make the code more readable/maintainable.</p>
<p><strong>My conclusion</strong>: I will not change my old queries but I will correct my writing style and use the keywords in the future.</p>

Nothing is wrong with the syntax in your example.  The 'INNER JOIN' syntax is generally termed 'ANSI' syntax, and came after the style illustrated in your example.  It exists to clarify the type/direction/constituents of the join, but is not generally functionally different than what you have.
Support for 'ANSI' joins is per-database platform, but it's more or less universal these days.
As a side note, one addition with the 'ANSI' syntax was the 'FULL OUTER JOIN' or 'FULL JOIN'.
Hope this helps.