This has been the year of Chipotle Mexican Grill (CMG). The stock is an absolute superstar, hitting 37 new record highs so far, according to CNBC.

Chipotle shares traded at $421.37 Tuesday, and are up nearly 26% this year. Over the last 12 months, the stock has gained 65%.

Truly amazing. Chipotle's run has obviously been the subject of much chatter among investors. Why is this stock so high, and how much further can it go?

There are two schools of thought. First is that Chipotle is just too expensive and simply can't maintain this growth. The other is that Chipotle's numbers are just headed up, and the stock has room to grow as well. I'll go over both lines of thinking in more detail below.

This stock is expensive

No one disputes that Chipotle is pricey. But is it worth that valuation? No, says Will Ashworth at InvestorPlace. One reason is because Chipotle is getting some tough new competition soon from Qdoba Mexican Grill, owned by Jack in the Box (JACK).

And Jack in the Box has big plans for Qdoba. It wants to increase the number of Qdoba restaurants to 2,000 from about 597 now, Ashworth reports. Chipotle is on a similar kick, planning to add at least 155 stores this year to the 1,230 already open.

It's getting harder for both companies to find prime real estate for the new locations, Ashworth writes.

Then there's new competition from Taco Bell, owned by Yum Brands (YUM). Taco Bell isn't about to give up any ground in the Mexican fast-food business, and is testing a new Cantina Bell menu with premium ingredients and higher-quality offerings.

Chipotle's price-to-earnings ratio is a fairly ridiculous 62.8. The industry averages 25.8, according to The Motley Fool.

But look at the potential

But others think the stock has plenty of room. Chipotle's same-store sales growth was 11.2% in 2011, 9.4% in 2010 and 2.2% in 2009, the Motley Fool reports.

And you can't talk about Chipotle's growth without mentioning ShopHouse, the Asian-themed restaurant the company has opened in Washington D.C. ShopHouse has been wildly popular with little to no advertising.

The success had opened up the possibility that Chipotle could very well strike gold a second time. The company isn't saying much about whether it will expand ShopHouse, but investors are certainly pricing the idea into Chipotle shares.

Chipotle has no debt and about $400 million in cash, according to Seeking Alpha. And Chipotle is in that best-of-both worlds position because it can compete directly with fast food, but also stand up against more upscale restaurants, such as Panera Bread (PNRA).

Finally, Chipotle is gunning for international expansion, recently opening new locations in London and planning one for Paris.

So what do you think, readers? Is this a stock to avoid or a stock that is just starting to hit the bigtime?

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