PedigreeBased on the PC series of the same name, the Zoo Tycoon games are rooted in the business / construction simulation titles that proved to be very popular in the 1990s. These types of games include the SimCity series and its numerous spinoffs, Theme Park, and the Civilization series. These sorts of titles usually appeal to those who take gaming very seriously; perhaps you could say "connoisseurs" of gaming. Thus, a certain level of quality and depth is expected.
Publisher THQ is neither fully innocent nor consistently guilty as a shovelware publisher. Developer Blue Fang Games is an interesting case in that the only games they've ever created are those in the Zoo Tycoon series. This game marks their first appearance on the DS, and one of only two games ever created for Nintendo's portable (the other being Zoo Tycoon 2 DS).
It's worth noting that while neither of the two PC Zoo Tycoon titles were excessively praised nor bashed, they have won numerous awards relating to its family-friendly play. I can't vouch for the prestige of any of these awards, but it's always interesting to find a disconnect between critics and award organizations.