It's been a staple in my studio since, and I don't think I'm going to get rid of it anytime soon.  It's just too useful and easy to program.  There are 50 preset patterns in ROM, and 50 more available in RAM for you to program, but really there are many more, because per each pattern you can save a pattern A, fill A, fill B and pattern B.  Step and real time programming are supported.

The sounds are oriented towards rock, but dig into the ROM and you'll find some useful sounds for electronic, Latin, pop, reggae, jazz... a little bit of everything.  I was very surprised (still am) that Alesis included TR-808ish samples, but the TR-909 is completely absent.  Oh well.

The Alesis SR-16 drum machine came out in 1990, and it's still being manufactured!  A perfect example of the "if it isn't broken, don't fix it" rule.  The secret to the longevity of this machine is the high quality of its on-board sounds, and a few features that make this an excellent choice for the gigging solo musician, such as separate pedals for start/stop and fill ins/outs.

Many sounds on the SR-16 use a technique called "Dynamic Articulation": this makes the timbre of a sound change slightly when the pads are stricken soft or hard, and adds a lot to the realism of this machine.

Although it does have a few electronic sounds on board, true to its American origin, the SR-16 is mostly focused on bread and butter "rock 'n' roll" sounds.  The snares in particular are absolutely beautiful, and various enough to approach any project with them.