NEW YORK (TheStreet) -- If you're expecting the new HTC One smartphone to be something completely brand new you might be disappointed. Your first clue: HTC didn't give this year's model a brand-new name -- it just changed the number to M9. HTC officials want to let you know there have been numerous upgrades and improvements. In the end, however, it's still an HTC One.

Not that there's anything wrong with that. The One has been and still is a terrific smartphone. But in the current world of larger Apple (AAPL - Get Report) iPhone 6 models (with more coming later this year) and the complete overhaul of Samsung's (SSNLF) Galaxy S phones, HTC needed to make a big splash of its own to get buyers to pay attention. The One M9 may not fit the bill.

What you need to know is that the new One M9 is a great smartphone made even better for 2015. On the outside, aside from a few styling changes the smartphone is instantly recognizable as a modern HTC design. A lightweight, dual-tone metal unibody shell protects the components and gives the device a luxurious feel. The edges are all rounded to perfection and the device oozes class. The M9 is slightly smaller in most respects than its predecessor. It measures 5.7 by 2.7 by 0.38 inches and weighs in at 5.3 ounces.

The larger differences are buried inside. Like the 5-inch, full HD LCD display. Or the eight-core Qualcomm (QCOM - Get Report) Snapdragon 810 processor, 3 GB of RAM, 32 GB of storage (along with a microSD card expansion slot), a 20-megapixel autofocus camera on the back to handle stills and up to 4K video, an HTC "UltraPixel" camera up front for 1080p videos, a 2840 mAh rechargeable battery and all the current, popular connectivity bells and whistles you can think of. Previous One fans should note that HTC has moved the on/off button from the top of the phone to beneath the volume rocker switch on the right-hand side.

As for software, the M9 runs version 5.0.2 (Lollipop) of Google's (GOOG - Get Report) Android operating system as well as a newly refined HTC Sense software feature set. In the past, Sense totally overpowered some Android features. This new version, 7.0, brings a bit more restraint and refinement and much less intrusion into your daily smartphone routine.

Our test unit was one of the first U.S. standard GSM handsets to reach our shores. It was programmed for T-Mobile US' (TMUS - Get Report) 4G/LTE network. That means it came loaded with T-Mobile's Wi-Fi calling option to route voice calls over your home (or office) Wi-Fi network. As in the recent past, we've found the quality of calls using T-Mobile's VoIP (Voice-over-Internet-Protocol) technology to be hit and miss depending on where you're standing in relation to the Wi-Fi "hotspot." Voice calls made on the M9 using T-Mobile's 4G/LTE network were solid indoors and out.

HTC prides itself on the quality of the sound emanating from its smartphones. The M9 has what HTC calls its "BoomSound" system consisting of stereo speakers above and below the screen and new Dolby (DLB - Get Report) audio software enhancements. It really does sound great. Don't expect disco/club playback levels, but what this phone does provide is quite nice. The M9 can handle most low- and high-resolution music file formats from mp3 to FLAC and WAV. The new phone also deals with an alphabet soup mix of video formats as well.

The new 20-megapixel rear camera is a welcome improvement over that UltraPixel system HTC was touting in previous One models. HTC engineers used to explain the use of lower-megapixel cameras by saying each actual pixel was larger than the competition's. Scientific reasoning aside, the new system produces much, much better photos, but it's still not the equal of Apple or other smartphone designs. The One's photography app is still one of the best in the business.

In our tests, the battery, which is not user-replaceable, lasted us a day with normal use. That included a lot of email, some voice calls, a little Facebook, Twitter, Spotify, Tidal, and Netflix, and a card/board game or two on long subway rides. We were concerned we would run out of juice at times, but the M9's battery did hold out with a large dose of judicial use.

One disturbing note: Our test unit seemed to exhibit a kind of smartphone "seizure" every so often. The device would freeze and we'd have to wait until the system allowed us to switch back to the home screen. We found that closing all of our open apps every once and awhile prevented the problem from recurring.

Overall, we loved our time with the M9. The refinements HTC has included with this year's model have improved what was had been a wonderful device. In a perfect world, on its merits alone, global sales numbers would top the charts. But these days the competition is fierce, and this new HTC One may not be "new" enough to overtake what's already on the market and what's coming in the near future.

You won't be making a bad choice if you like what you see and buy a M9 right now, but we think the majority of potential customers may take a wait-and-see attitude. That could prove to be a problem for HTC and a shame for the One M9. It's a worth a second look.

Overall Score: 8.5/10

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.