I had a small one "Dr. Boss" years ago, and its' best feature was you could play it like an instrument, tapping on these rubberized buttons. Adds a little human touch. It died and I never got another one, since you can do the same thing on any computer nowadays. If you don't need the portable machine for gigs, just get a free Midi program and create your own patterns on channel 10.
Playing with them is great, you get rock-solid with your timing.
Oh, one advantage to working out drum patterns on the computer, you can really get in there and fine-tune the notes so they sound natural. You can change the attack (volume) on each note, so they sound more lifelike. Likewise, you can scoot notes off the beat a little, to rush or to lag, to sound more organic. The more time you spend, the less anyone can tell it's a machine. I once worked out a flute solo without a flute that sounded very lifelike, and it got played on the radio.
Also, if you go with the computer, try Band in a Box which gives you more than just the drums - also bass and piano and more. Some of it is cheezy but you can get in there and change things.