The DS1102E is an excellent scope, and Rigol has done an amazing job of lowering the cost of entry for good quality scopes.
Another option at the same price is the DS1054Z:
https://www.adafruit.com/products/2145 Twice the channels, but half the bandwidth (50MHz as opposed to the 1102E's 100MHz).
As a rule of thumb, assume you need a scope whose upper limit is 5 to 10 times the fastest signal you want to measure. That's especially true for digital signals, because the rising and falling edges of square waves are bundles of high-frequency information. A 50MHz scope can't tell the difference between a 50MHz square wave and a 50MHz sine wave. The more headroom you have between your signal and the scope's upper limit, the more useful information you can get about the fastest parts of the signal.
My day-to-day scope is a 100MHz 4-channel Tek, and I really like having four channels.
Most of what I do involves looking at the relationships between signals: Does the output behave as expected for the given input? How much lag is there from this part of a circuit to that part? etc. You can do simple comparisons with a 2-channel scope, but with four channels I can probe multiple points along a signal path.