(MD-MT15 is similar but has no remote, and uses AA cells)
It's rather thicker, but shorter, than the Sony MZ-R50. Kind of thick for keeping in a pocket. Could use a belt-attached case. Alas the carry bag that comes with it is simply that: a soft, thin cloth ("fleece"-like) bag with a drawstring. (But it is better than nothing.) The earphone socket is on one end so that a narrow belt-case I used it in allows the earphones to be plugged in while in the bag - unlike the Sony MZ-R50 where the earphone socket is on the side, requiring a wider case.
A nice touch (missing on the Sony MZ-R50, and that has caused me grief): one corner has a hole apparently for attaching a thin strap. Use one consistently and save your unit from falls!
Straightforward user interface for most operations. (But not for editing...) The main buttons are designed so that one can identify them by touch, without looking. Some buttons serve multiple purposes, but in a logical way. E.g., Stop and Off are the same button, Play and Pause are the same button, and the FFWD/RWD buttons are used whenever anything needs to be adjusted up/down (setup options, track number, position within track, recording level, etc, but not playback volume: volume has its own 2 up/down buttons, although the "less volume" button also doubles as a "turn on the charging" button). See more below about those FFWD/RWD buttons.
The MT15 has a "hold" switch to prevent accidental turn-on while in a pocket, etc. (So does the Sony.)
The display cannot show track name and time simultaneously. (It does display the track number along with its name.)
No real-time clock, but the MT15 can add track marks while recording, every 3 or 5 or 10 minutes. (I wish it could add such marks to an existing recording, sort of a "bulk-divide" editing option, but it cannot, nor can any other unit that I know of...). The Sony in comparison has a real-time clock that it will date-stamp recordings with.
While playing, the fast-forward and fast-rewind buttons move through the music at about 4 times the normal speed, and one can hear snippets of the music while it does it. While paused, the same buttons move through the data at a rate of about 1 minute of music for every 2 seconds of holding the button down. There seems to be no "acceleration" feature, like, e.g., the Sony MZ-R50 has, where the "winding" starts slow and gets faster after a few seconds. (Acceleration can be helpful, and I find it good on the MZ-R50, but can be a pain, as it is on the MDS-JE520 home deck, where it is way too slow for a while and then all of a sudden it is way too fast, and I find myself going back and forth and constantly overshooting, and, on the JE520, if I hit "stop" by mistake (instead of "pause") then the JE520 completely forgets where it was... so perhaps the no-acceleration design of the MT15 is acceptable.) But watch out: a quick tap on the same button brings you directly to the next track (or the beginning of the current one), so if you are in the middle of a long track and mean to move just a bit, don't hit the button for too short a period or you may have to suffer through a long un-accelerated button-press to get back where you were.
On the MT15 one can change recording level manually while recording. In recording a live show with varying sound levels, this feature is invaluable. I may prefer the MT15 over the MZ-R50 for live recording for this reason alone. The dB-meter is (relatively) large and detailed (in 2-dB steps up near "0"), responds very quickly, and also has a more persistent peak level indication. The range of mike sensitivity available is very large: from whisper-across-the-room level to concert level. (All with the same cheap condenser mike, not included...)
The MT15 has "sync" recording capability (stops and restarts, adding a track mark, upon periods of silence). This mode is available for both line and mike analog inputs.
The included headphones are apparently of fairly high quality (large ear pieces, gold-plated plug) and produce much higher audio volume than other (cheap) headphones I've tried.
Also included was a stereo mini-phone-plug to RCA cable, to connect the unit to a home stereo. Nice touch! I like to have TWO such cables permanently connected to my home stereo, one to the AUX or TAPE IN (cable labeled "PLAY") and one to the TAPE OUT (cable labeled "REC"), thus I don't need to fiddle with plugs behind the stereo system every time I want to play from or record on a minidisc.
THe MT15 remembers its position in a disc even while turned off. (So does the MZ-R50, but not the JE520 home deck, where merely pressing the Stop button instead of the Pause button causes it to totally forget where it was!)
The instructions say not to use batteries other than standard AA alkalines or the official rechargable pack. But since the official pack is NiMH (2.4V), I figured it won't hurt to try other rechargables. Seems to work just fine for me on a pair of AA NiCads. (But don't blame me if you do this and it destroys your unit!).
I did not buy the optional rechargable battery pack. The drawings in the manual seem to show that it is two AA-size NiMH cells connected together. But when I put two rechargeable (NiCad) AAs in the unit, and plugged in the charger, and pressed the "charge" button (which is required to start the charging, and one cannot charge while playing), it refused to charge my AAs. It appears that the official battery pack has additional connections (on the side) that tell the unit when it is OK to charge. Thus, if one uses AA rechargables one needs to take them out to recharge them in another charger. Runs for hours on the Nicads, but not for as long as alkalines or NiMH. "Renewal" rechargable alkalines also work.
The AC adapter that came with this MT15 is a cheap and heavy transformer type, not a switching supply like the one that came with the MZ-R50. I've heard that a Sharp switching supply does exist. If you don't carry the adapter with you on the road then this is not a problem. When I plugged the Sony AC adapter into the Sharp (by mistake), the Sharp displayed a "POWER?" warning message, then went blank, with no damage. (The Sharp adapter is rated 5V 800mA, and I measured about 5.6V from it with no load. The Sony adapter is rated 6V and the open-circuit output is about 7.5V. Polarity is same.)
Conclusion: the MT15 is a nice no-frills portable recorder, does the job. Will be a good deal when its street price falls to about $150 in a few months? (Current (12/99) official price is $200.)
It isn't difficult to tape a couple of AA NiMh cells together and tape or glue something in the dip between them to activate the switch. The hardest part is finding exactly how far along the cells the something needs to be. Suggest you start by using a small rod pushing the finger all the way in to estimate the distance and then make minor adjustments by trial and error. If the something isn't far enough along then the switch doesn't get activated and charging won't happen. If too far, the battery pack won't go fully home into the compartment and you won't get the door shut.
I had no problem running or charging from a regulated 4.5 volt AC adaptor.
All above info for use at your own risk. Especially I wouldn't advise using the internal charger with rechargable alkalines.
PS Your European readers might be interested to know that the MT15 in USA seems very similar to the MT16 in Europe. That too comes without the remote, battery pack, optical lead and AC adaptor that are in the MT20 package. From your review I understand that MT15 includes the AC adaptor. The AC adaptor supplied with the MT20 here in the UK is a conventional (heavy) transformer and is 240 volt input only. There exists (at least in Japan where I saw them at a time when I had little interest) a lightweight 100-240 volt adaptor.