Apple (AAPL 0.51%) stock has had a great start to 2023. Shares have risen about 17%, easily surpassing the S&P 500's 7% gain over this same period. But one analyst thinks the stock still has plenty of room to run. KeyBanc analyst Brandon Nispel reiterated an overweight rating (similar to a buy rating) and a $177, 12-month price target for the stock on Tuesday. The target translates to about 16% upside from where shares are trading at the time of this writing.

Is Apple stock really still this attractive, even after its recent run-up? Let's take a look at why Nispel is bullish on the stock and attempt to determine whether or not shares are a buy today.

The path to $177

Some of the keys behind Nispel's optimism for Apple stock are expectations for user growth across the tech company's installed base of products, and recent optimistic commentary from Apple management about the company's important China and India markets.

Regarding Apple's user base, Apple CEO Tim Cook said in the company's fiscal first-quarter earnings call that its installed base of active devices recently surpassed 2 billion -- up about 150 million year over year. Furthermore, user engagement is improving, too. For instance, Apple said in its last quarterly update that its paid subscriptions across its services platform now total 935 million. This is also up about 150 million over the last 12 months. In addition, this level of subscriptions is up four times from where it was only five years ago.

Looking to China, Apple seemed happy with the company's progress there. As COVID-19 restrictions eased in December of 2022, there was "a marked change in traffic in our stores as compared to November," Cook explained. "And that followed through to demand as well."

In India, Apple is firing on all cylinders. The company's revenue in the market grew at a "very strong" double-digit rate during fiscal Q1. Cook emphasized that it's a "hugely exciting" market for the company.

Is Apple stock a buy?

These three catalysts are, indeed, good reasons to be bullish on the tech giant's underlying business. But what about the stock? With a price-to-earnings (P/E) ratio of nearly 26 at the time of this writing, shares aren't exactly cheap. Furthermore, it's not like everything is going well at Apple. Some disruption to production in fiscal Q1 and macroeconomic uncertainty weighed on results, leading to revenue falling 5% year over year.

Overall, however, a P/E ratio in the mid-twenties isn't a bad price to pay for a company with such an impressive track record with growing its user base and delighting its customers. In addition, the company's massive, loyal customer base should be a boon for earnings growth over the long haul. While shares aren't a screaming buy at this level, the stock remains attractive. Though anyone buying Apple stock at this level may want to keep the position small relative to their overall portfolio. A higher price means the company needs to execute exceptionally well over the next decade in order to live up to the current valuation.