It is sort of sad that every time a game that is even slightly similar to DF (even simply one that involves dwarves in some way) people leap all over it as stealing ideas (Heard it about Dwarfs!?, Delve Deeper, and even Minecraft early on).
As for the comment made.. I cannot say I haven't heard it before and like most criticism there is a kernel of truth to it, unfortunately like most criticism its also blown way out of proportion and steeped in bias. Yes there are flaws with DF, however ultimately I think its one of the better, of not the best, game I've ever played (its certainly the game I've played the longest). It gets far more support than most games (particularly a free game) and has been consistently updating itself for about a decade now. In addition, since I started playing back in 40d, despite its flaws it has always been 'playable' (save for some game-breaking bugs that occur near major releases that are always dealt with quickly), which is more than you can say for many AAA titles.
Push comes to shove, nobody has to love DF, its got some major flaws that do a lot to unnecessarily increase the barrier to entry (the UI perhaps being the prime example of that) and I'm sure everybody has their pet feature they wish were focused on and/or fixed.. But its a great game, its playable, and most importantly its a unique experience. There are lots of shooters, there are lots of RPGs or RTSs, but there are like a half-dozen games that are even slightly similar to DF, and most of them are far more simplistic and/or suffer from their own flaws.
Best of all though, DF is continuing to update, free of charge, to this day, but if they stopped tomorrow I'd still have a game that is uniquely awesome and has sucked up a truly embarrassing amount of my time.