Yes, the Aladin One is the entry-level model, then there is the Prime, and then the Tec2G.
To be honest, the Prime is a nearer match to the Gekko, in that you can switch nitrox mixes on the computer itself, etc. The One is very basic and, while ideal for a rental situation (it doesn't have any buttons so renters can't screw around with it), it does limit its use, particularly on trips - you wouldn't want to have to piss around with a PC to change the nitrox mixes.
It is a good computer in terms of how it performs underwater, but unfortunately, I'd say you have been slightly mis-sold. If you were looking at a Gekko and they put you on to this, then they have done you a bit of a mis-service - I'd have offered the Prime as an option as it offers virtually the same usability as the Gekko. You will soon out grow the One...
Mark