I have the Logicport, and have used the I2C, SPI, and UART decoders. I wish it had a 1-wire decoder, and that the UART decoders either (1) auto-detected the baud rate, or (2) could be sync'd together so I don't have to change all the decoders if I change baud rate. You set up one decoder for each line you're monitoring, so for a full SPI you need two decoders - one for Tx, one for Rx. Same for UARTs. You also must specify a chip select line for SPI. You can, however, attach multiple decoders to a single line, which is handy when you want to see both ASCII and hex values at the same time, or if you have an SPI bus with multiple chip selects.
The only real drawback with it is the 4k sample buffer, which is enough for 99% of my needs (esp with compression enabled), but occasionally when I'm watching a serial data stream or 1wire transaction, more RAM would be nice.
The adjustable trigger voltage is nice; I've used it to hunt down glitches and ripple. The 500MHz setting is great for glitch hunting and edge timing.
The 40-pin connector is just the right size to plug in an IDE cable, too, which is handy, as you can see in this picture:
The cable makes the logicport "breadboard compatible" and I can just unplug the whole cable if I need to use the logicport anywhere else, without having to reconnect all the individual wires later.
The save/load features work as expected; I have configurations for each of my prototype and test boards, like an RS-232 breakout I built. Prints are nice, but it helps to use the dark-on-light screen theme so that the printout resembles the screen, otherwise the colors aren't always readable (it won't print a black background, just light colors on white).
There are six "cursors" you can place, and measure time or frequency between them. The precision of the sampling period seems to determine the number of significant figures they're displayed in, which is nice. Handy when checking clock speeds or UART baud rates.
I haven't upgraded my software in a while, so there may be other neat features I don't know about, too.
We are using it, it works really great! 10ns resolution even with very long measurements. One disadvantage is the fixed threshold, you might want to buy the (more expensive) DV3400 if you have other than 3,3..5V logic signals.