For people who read a great deal, it's sometimes hard to decide between using a tablet and an e-reader. Can you use the device in your backyard on a sunny day? Is it comfortable to hold in one hand? Can you read in the dark without having to buy a separate clip-on light?

If you've got an e-ink reader like Amazon's Kindle Touch, the answer is yes to the first two questions and no to the third. If you're using a tablet such as the iPad, your answers will usually be reversed.

Barnes & Noble Nook Simple Touch with GlowLight

As someone who has gone through a variety of clip-on lights without finding one that I thoroughly liked, I've compromised by using my smartphone as an e-reader. Barnes & Noble has now come out with a new version of its Nook Simple Touch e-reader designed to offer the clarity of the E Ink technology along with LED lighting that enables it to be used in low-light (or no-light) conditions.

I had a chance for a quick hands-on with a sample unit a few hours before it was announced. On the whole, I was impressed.

The Nook Simple Touch with GlowLight ($139; expected to ship in early May) illuminates the reading surface with 8 LEDs embedded in the upper inner edge of the bezel, just above the display. You turn these LEDs on by pressing on the button just below the display for a couple of seconds. A quicker press brings up a menu along the bottom; tap on the selection labeled "GlowLight" and you can adjust the intensity of the light via a sliding control.

Otherwise, there are few differences between this Simple Touch and the one already on the market. Both have the same 6-in. e-ink display, 802.11n Wi-Fi, 2GB of storage and a slot for an SD card. At 6.5 x 5.0 x 0.47 in., the GlowLight has the same dimensions as the non-lit version (although at 6.9 oz., it weighs about an ounce less).

According to a Barnes & Noble representative, the new Nook will last a month on a charge with wireless off, based on a half hour of daily reading with the GlowLight on (the count goes up to 2 months with the light off).

Nicely lit -- but will it sell?

When I tried it out in low light conditions, the new Nook looked as though it could work nicely as a nighttime reader -- the lighting seemed evenly spaced across the screen and was comfortable and glare-free even at its brightest setting. The LEDs were just visible along the top of the display if I looked for them; while they appeared green to my eyes, the B&N rep assured me that they were actually as neutral a color as possible. (He added that the development of the lighting technology was done in-house.)

The question, of course, is whether there is still a market for a dedicated e-reader -- even one that now allows you to comfortably read at night -- especially for the asking price of $139.

It's a close call. The current, almost identical Nook Simple Touch costs $99. Its direct competitor, the Kindle Touch, also costs $99 with ads, but shoots up to $139 without (neither of the Nook e-ink readers includes advertising).

Other comparison points: The Simple Touch with GlowLight comes with an AC adapter while the Kindle Touch doesn't (one can be had for an additional $15), and if you want to add a clip-on light to the Kindle, it will probably cost you about $20. On the other hand, the Kindle does come with audio, so you can listen to music while you read or have text read to you; the Nook Simple Touch (with or without lighting) does not.

Bottom line

The market for tablets and e-readers is in a great deal of flux. It feels as if new models are arriving almost on a weekly basis, with prices changing at almost the same rate. Reasonably equipped Android tablets are available for $250 (and prices may dive even lower ). Consumers can now buy color Web-friendly tablet/e-readers such as the Kindle Fire and the Nook Tablet for $200. And, of course, budget-minded buyers can get a number of e-ink readers for under $100. So how likely is it that the Nook Simple Touch wtih GlowLight will attract buyers?

Personally, I'm not optimistic -- but who knows? The wide popularity of e-readers (and the price battles currently raging among e-book suppliers and publishers) shows that there is still a large population of enthusiastic readers out there, many of whom don't necessarily want to schlep around a 1 lb.-plus tablet that will use all its juice in a few hours. People who really enjoy reading -- and who don't mind spending a little more in order to read comfortably in bed -- may find that the Nook Simple Touch with GlowLight is well worth the slightly higher price.

Barbara Krasnoff is reviews editor at Computerworld. When she isn't either editing or reviewing, she blogs at The Interesting Bits ... and Bytes; you can also follow her on Twitter (@BarbaraKrasnoff).